Method for producing metal containing composite and metal containing composite formed by adhesion

ABSTRACT

An adhesive (B) of solvent containing adhesive as a suspension of low viscosity is prepared by adding a solvent MIBK to a one-part epoxy adhesive of a dicyandiamide-curable type (A). Metal shaped articles (M 1  to M 5 ) as adherends are prepared each of which, through various surface treatment, has specific surface configuration of roughened face and/or ultrafine irregularities and the surface is entirely covered with a thin layer of ceramics such as a metal oxide or metal phosphate. The specified face of each metal shaped article (M 1  to M 5 ) is painted with the solvent containing adhesive (B). The faces painted with the adhesive of two metal shaped articles (M 1  to M 5 ) are caused to abut each other, the articles are heated to cure the one-epoxy adhesive to accomplish adhesion. With one of the adherends replaced by a CFRP shaped article (P 2 ), a composite of a metal and CFRP can be formed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of and claims the prioritybenefit of a prior application Ser. No. 15/153,670, filed on May 12,2016, now allowed. The prior application Ser. No. 15/153,670 is based onand claims priority under 35 U.S.C. § 119 to Japanese Patent ApplicationNo. 2015-97750, filed on May 12, 2015. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

TECHNICAL FIELD

The present disclosure relates to a method for producing a metalcontaining composite and to a metal containing composite formed byadhesion. More particularly, the present disclosure relates totechniques for strongly integrating, by use of an epoxy adhesive, ametal part with another metal part or a metal part with a CFRP (CarbonFiber Reinforced Plastic) part and provides practical use of a methodfor integrating a metal part with another metal part or a metal partwith a CFRP part in place of an assembling method with bolt and nut, bywelding, by tight fitting or the like. The present disclosure deals withall kinds of metal including copper, steel, magnesium alloy, aluminumalloy, titanium alloy or the like and can be applied to generalmachines, medical instruments, electrical machines, moving machines andother various kinds of machines, and also to manufacturing thesemachines.

BACKGROUND ART (As to CFRP)

CFRP is called in another more precise manner as CFRTS (Carbon FiberReinforced Thermo-Set Plastics) and is ordinarily a shaped article ofresin having a matrix resin of thermo-set epoxy resin. While CFRP hasbeen used recently in structures of aircrafts or automobiles, this owesto its mechanical properties of superlight weight and high strength.However, in the passenger aircraft B787 in which newest CFRP is usedabundantly, rivet connection as a conventional fixing technique isemployed for connecting a wing member of CFRP to another of CFRP and forconnecting a CFRP member and an Al-alloy A7075 (extra-super-duralumin)member.

While CFRP contains bundles of carbon fiber (abbreviated as CFconveniently below), cloths of CF or the like abundantly, it is a shapedarticle of epoxy resin or thermoset plastic. Due to this, bolt and nutconnection cannot be used for connecting CFRP with another member of ametal part or the like. Overfastening with a nut may break a CFRP memberas a shaped article of resin. Assembling methods were studied forconnecting various CRFP members each other regarding passenger aircraftsof the Boeing Company (USA), a manufacturer of aircrafts.

After all, a method was employed such that through-holes are formed atthe end of each CFRP member, rivets of Ti-alloy, of which the outerdiameter is coincident with the through-holes, are pushed into thethrough-holes, and two members are connected for assembly.

However, it is not an easy matter to perform precision working of twokinds of CFRP members to be connected so that the diameters of thethrough-holes formed therein are in the level of “rivet diameter+0.1mm”. Further, tremendous number of rivets is necessary for manufacturingan aircraft and the number of working steps required for formingthrough-holes is beyond supposition. If a metal alloy member can bejoined with a CFRP member at the end of it with an adhesive to have highjoining strength and reliable adhesiveness, wings or a body structure ofan aircraft could be assembled easily by connecting one metal alloymember joined at the end side with another metal alloy member joined atthe end side using bolt and nut. Further, if members, in each of which aCFRP part is joined with a metal alloy part, are formed and a metalalloy part of one member can be joined with the CFRP part of anothermember with high strength of adhesion, an aircraft could be obtained inwhich all parts are integrated by adhesion via metal alloy.

Here, in conventional techniques, it is clarified that a metal alloysubjected to specific surface treatment (see Patent Documents 1 to 9 bythe present inventor for NAT (Nano Adhesion Technology) theory) can bejoined with another member with extremely high joining strength ofadhesion estimated by shear breaking strength of adhesion as ameasurement of adhesive strength. However, while tensile breakingstrength varies corresponding to metal species regarding tensilebreaking strength (maximum tensile strength) of adhesion, clear reasonof adhesion could not be explained yet. Further, theoretical explanationwas not established yet as to what a level of maximum shear breakingstrength or tensile breaking strength can be obtained using a specificone-part epoxy adhesive, and also as to the theory, that is, from whatthe strength comes. For this sake, it could not be decided what is to beimproved further for making tensile strength of adhesion (maximumtensile strength) have a value near the maximum.

To say this regarding materials for an aircraft, it is necessary todevelop a method for obtaining the maximum strength of composites of NATtype (composites obtained by adhesion according to NAT theory) ofAl-alloy with Al-alloy, Ti-alloy with Ti-alloy and these with a CFRPmember, and also to establish its theoretical explanation. However,there has not been sufficient development of a method or theoreticalexplanation for this yet. Techniques of accomplishing a light weightstructure combining duralumin members, Ti-alloy members, CFRP members,or the like that are of light weight and rigid are important ones intimes of energy-saving that will continue yet after now. If reliableadhesion techniques can be attained, it will form a core of suchimportant techniques. Therefore, the above mentioned is importantespecially for moving machines such as aircrafts, automobiles, or thelike.

(As to Current NAT Theory)

Here, summary of the conventional NAT theory established by the inventorwill be explained. NAT theory concerns techniques for joining strongly ametal part with another metal member or a metal part with a resin partby use of an adhesive and the following conditions are required asregards metal materials, adhesives and adhesion steps. That is:

(1) The metal material has a roughened surface with convex-concaveroughness of 0.8 to 10 μm (Rz) period (roughened surface of micron orderperiod). (2) Further, there is fine irregularities of 10 to 300 nmperiod on the above roughened surface.

(3) The surface layer having a surface formed with dual irregularitiesof the above (1) and (2) consists of at least one hard thin layer ofmetal oxide, metal phosphate and other ceramics.

(4) A one-part epoxy adhesive is used as an adhesive.

(5) In operation steps of adhesion, there is an operation step of“impregnation” as an operation step for causing the adhesive topenetrate into the bottom of the fine concaves of the irregularities onthe surface of the metal member.

While NAT theory is one established by the inventor, it was at first ahypothesis (supposition). However, the inventor practiced the above (1)to (5) for various metal species and confirmed that adhesion strengthattained with NAT theory usually exhibits values twice of data withoutNAT theory. From this, the inventor has come to recognize the hypothesisas a correct theory. Results demonstrating the recognition are disclosedin Patent Document 1 for aluminum alloy, Patent Document 2 for magnesiumalloy, Patent Document 3 for stainless steel, Patent Document 4 forcopper, Patent Documents 5 and 6 for titanium alloy, Patent Document 7for general ferrous material, Patent Document 8 for aluminum-platedsteel sheet and Patent Document 9 for zinc-plated steel sheet,respectively. Most of these have already been commercialized in thefield of electronic machinery, moving machinery or the like, or are inthe stage of provisional manufacturing before mass production.

(New NAT Theory)

Adhesive strength of a metal part with another metal part increasedtwice as before the above NAT theory, thus practical use of it isbeginning as mentioned above. Further, it was necessary to change themethod of measurement in order to measure the strong adhesion correctly.The inventor adopted a piece comprising two small pieces in which endsof two small pieces of 45 mm×15 mm×3 mm (thickness of 3 mm) are lappedeach other and caused to adhere with an adhesive (adhesion area of 0.5to 0.6 cm²) and used the piece comprising paired small pieces as aspecimen for measuring “shear breaking strength of adhesion”, instead ofthe method of measurement by JISK 6849 (ISO 6922) “Method for testingtensile strength of adhesive”.

Similarly, as to a specimen for measurement of “tensile strength ofadhesion (maximum tensile strength)”, small pieces of 18 mm×4 mm×3 mmwere used at first, instead of following JIS 6850. The respective edgefaces (4 mm×3 mm) of two of the small pieces were caused to confronteach other and adhere with an adhesive to form a specimen formeasurement, which was then subjected to tensile breaking formeasurement of tensile breaking strength of adhesion. However, thisspecimen exhibited an inferiority such that there is much dispersion indata of measurement because bending moment is apt to be applied on thespecimen depending on a manner of fastening, with chucks, the bothgripped ends of specimen comprising two joined small pieces with totallength of 36 mm when the specimen is to be pulled off in a tensile test.From this, configuration of specimens the inventor uses came to be of asmall piece as 50 mm×10 mm×2 mm (the end face of 25 mm×3 mm is foradhesion), and then recently came to be of an elongated small piece as100 mm×25 mm×3 mm (the end face of 25 mm×3 mm is for adhesion), which isdecided to be favorable because dispersion of measured values becomesless.

In short, while NAT theory became spreading, “tensile strength ofadhesion”, for which measurement is difficult among strengths ofadhesion, has been left almost untreated without measuring in contrastto “shear strength of adhesion”, for which measurement is easy. Recentcircumstances have changed this situation. NAT theory is superior not inadhesion of a metal member and another metal member, but also inadhesion of a metal member and a CFRP member, thus it has come to beremarked in industry of moving machines, especially by firmsmanufacturing automobiles, aircrafts, or the like. As derived by this,various official committees are inaugurated under the leadership ofMinistry of Economics and Industry in Japan and working has begun forproposing new standard methods of ISO regarding methods for measuringstrength of adhesion of joined articles with adhesives comprising metalparts, CFRP parts or the like.

As a result, concern of tensile strength of adhesion has become higherand the inventor has come to study improvement of the method formeasuring tensile strength of adhesion that are to be submitted to ISO.While studying such, it became clear that what exhibits true strength ofadhesion between a metal part and an adhesive is not shear breakingstrength of adhesion but tensile breaking strength of adhesion, andthat, strictly speaking about the surface configuration of the metalalloy material exhibiting the maximum tensile strength of adhesion, thesurface configuration of the metal part according to NAT theory is notnecessarily required. The inventor thought this as coming nearer to theessence of joining technology with adhesives and thought of establishinga new theory (New NAT Theory) by summing and arranging these matters. Inshort, it seemed that the New NAT theory that will be explained laterwill bring reliability of joining technology with adhesives to each ofthe above mentioned machine manufacturing industries.

PRIOR TECHNICAL DOCUMENTS Patent Documents

-   [Patent Document 1] WO2008/114669-   [Patent Document 2] WO2008/133096-   [Patent document 3] WO2008/133296-   [Patent Document 4] WO2008/126812-   [Patent Document 5] WO2008/133030-   [Patent Document 6] JP Published Patent Application No. 2010-064397-   [Patent Document 7] WO2008/146833-   [Patent Document 8] WO2009/084648-   [Patent Document 9] WO2009/116484-   [Patent Document 10] JP Published Patent Application No. 2011-6544-   [Patent Document 11] JP Published Patent Application No. 2011-26457-   [Patent Document 12] JP Published Patent Application No. 2011-148937

Non-Patent Documents

-   [Non-patent Document 1] “Improvement and evaluation of adhesion    durability”, Joho-kikou-sha, 1^(st) Edition, 2012, pp. 372-374-   [Non-patent Document 2] “Technology Books: Selection of adhesive    creating high performance”, 7^(th) Edition, Katsuhiro Maeda,    Gijutsu-Hyoron-sha, 1992, p. 51

SUMMARY Problem to be Solved by the Disclosure

The inventor carried out plenty of chemical treatment experiments in atrial and error manner, plenty of observations with an electronmicroscopy, plenty of measurement tests of tensile strength of adhesion,or the like. With these, the inventor confirmed at first that the shearbreaking strength of joined pairs of two metal pieces (test pieces) thathas been subjected to surface treatment according to NAT theory is 70 to80 MPa, irrespective of metal species, in the case where a one-partepoxy adhesive, for example, “Scotch Weld EW2040” (made by Three M JapanCo. Ltd.: Main company in Tokyo, Japan) is used, and that the tensilestrength of adhesion is 40 to 80 MPa, with variation depending on themetal species. Meanwhile after then, it became apparent that the threeconditions of surface treatment of metal materials according to NATtheory is not necessarily required. Changing treatment method for metalmaterials according to New NAT theory as improved from NAT theory,tensile strength of adhesion of 90 to 100 MPa was confirmed for Ti-alloyand then a treatment method was found that tensile strength of adhesion,having been 80 MPa, increases up to 100 MPa also for Al-alloy.

In short, while “tensile strength of adhesion” that seems to truly showstrength of adhesion was not observed with NAT theory, the maximum oftensile strength of adhesion using a one-part epoxy adhesive came to alevel of 100 MPa. To say of the present disclosure concretely, itconcerns a method for raising tensile strength of adhesion of a piececomprising a pair of metal pieces joined together up to a level of 80 to100 MPa and discloses its content. Further, the inventor clarifiedconcrete methods for obtaining the extremely high tensile strength ofadhesion. The theoretical content is referred to as New NAT theory andit is explained in the specification that New NAT theory is somewhatdifferent from previous NAT theory. It is considered that reliance onNew NAT theory brings application of joining technology with adhesivesmore widely to various machine manufacturing industries.

(Content of New NAT Theory)

It was explained that NAT theory requires the aforementioned fiveconditions as to surface situation. Meanwhile, it was made clear thatthe aforementioned “(1) The metal material has a roughened surface withconvex-concave roughness of 0.0.8 to 10 μm (Rz) period (roughenedsurface of micron order period)” and “(2) There is fine irregularitiesof 10 to 300 nm period on the above roughened surface” are notnecessarily required. Then, taking electron microscopic photographs ofother various metal surfaces obtained through various chemicaltreatments into consideration, in addition to a model of treatmentaccording to NAT theory taking it as a required condition that metalmaterials have dual irregularities of roughened surface withconvex-concave roughness of 0.8 to 10 μm (Rz) period and fineirregularities of 10 to 300 nm period on the roughened surface, aschematic depiction of sectional configuration near the surface of ametal piece having been subjected to chemical treatment was made asexplained below.

Then, studying through contrasting this configuration analysis withactual measurement results, it became clear that the above definition ofa surface with dual irregularities is not necessarily required to clingonto, though it is not wrong as a concept. Here, FIG. 1(a) to FIG. 1(g)are schematic views showing various sectional configuration of jointfaces. FIG. 1(a) is a schematic view showing the concept of basiccondition of a surface with dual irregularities required by NAT theory.The sectional configurations shown in FIG. 1(b) to FIG. 1(g) containones coincident with the basic condition and also others not coincident.Thus, as can be said from contrasting these configuration views withactual measurement values, though shear strength of adhesion of piecesformed by joining with adhesives does not vary depending on theconfiguration of various fine irregularities formed on the metalmaterials, tensile strength of adhesion varies, thus the configurationof various fine irregularities itself being essential element.

At first, while it is supposed that “tensile strength of adhesion” to beobserved in Al-alloy is near the maximum, the configuration is not suchthat has surface roughness of micron order, but such that there areconcaves of 20 to 100 nm diameter, the concaves are of a bowl shape andform an orderly aggregate of ultrafine concaves. FIG. 1(g) shows aschematic view of its sectional configuration. The ultrafine concaves ofa bowl shape, which are of a “U-shaped valley type”, should grip resin(cured adhesive) securely. In short, it is a required condition inoperation of adhesion according to NAT theory to carry out operation of“impregnation (penetration deeply into the bottom)”. It was consideredthat if this operation is carried out neatly and securely, adhesive canpenetrate into even concaves of 20 nm diameter and then be cured toexhibit a high joining strength, in the case where a one-part epoxyadhesive is used.

This is a basis for presuming that “ultrafine concaves of bowl shape”shown in this schematic view, that is, the sectional view of FIG. 1(b)is one of the most excellent form. It is a pity from such understandingthat tensile strength of adhesion was attained merely up to 80 MPa fortest pieces of Al-alloys A5052 and A7075 having been subjected totreatment according to NAT. As there were some other test pieces forwhich tensile strength of adhesion up to 90 MPa was attained, it wasclarified that treatment method according to NAT the inventor carriedout previously was not the best. Then, the inventor endeavored to comenearer to “ultrafine concaves of bowl shape” shown in the schematic viewof FIG. 1(b), further adding trial and error to surface treatment methodaccording to NAT. As a result, a surface treatment method is found andinvented with which tensile strength of adhesion of 100 MPa can beattained.

However, such an ideal configuration cannot be obtained with othermetals. FIG. 1(c) shows a schematic sectional view of a model ofaustenite stainless steel such as SUS 304, which has a feature such thatroughened surface of micron order forms configuration of “V-shapedvalley type”. In this case, while shear strength of adhesion issufficiently high as comparable with the above Al-alloy, tensilestrength of adhesion is somewhat lower. This is because that, eventhough adhesive has penetrated into the bottom of the concaves on themetal material surface and been cured, stress concentration occurs inthe upper portion of the V-shaped valley and the area of the upperportion is merely ten and some percent of the joint face. Meanwhile,FIG. 1(d) is a schematic view showing a “step-like shape” of a commonsteel member represented by SPCC (cold-rolled steel plate). The samemetal material that has been subjected to treatment according to NAT hasa surface of fine irregularities with a configuration in which the“step” is inclined (the fine irregularities come from pearlitestructure).

In this case, tensile strength of adhesion varies depending on theinclination angle of the step profile. While dispersion is apt to occurand seems to be of a level in the mean value higher than stainless steelas a result, there is an inferiority in a simple configuration ofstep-like irregularities itself. Then, FIG. 1(e) is a schematic viewshowing sectional form of a model of a kind of pure titanium containinga tiny amount of oxygen subjected to treatment according to NAT and FIG.8 is an electron microscopic photograph of its surface. The micron orderperiod of roughened surface shown in FIG. 1(e) is somewhat large as 5 to20 μm and there are cases where the concave-convex period in the surfacewith fine irregularities amounts to 100 to 500 nm. This concave-convexperiod in the surface of fine irregularities of 100 to 500 nm is largeas compared with one according to the condition of NAT theory. Theconvex such as protruding from a plain is shaped as a steep mountain andis higher than what was presumed according to NAT theory. While it was aquestion how this acts on adhesion strength, both “shear strength ofadhesion” and “tensile strength of adhesion” were low as a result.

On the other hand, sectional configuration shown in FIG. 1(f) and FIG.1(h) was derived from the model of the sectional configuration of afirst species of pure titanium shown in FIG. 1(e). That is, it wasderived supposing that working treatment towards ones having sectionalconfiguration shown in FIG. 1(f) and FIG. 1(h) might be possible throughconversion treatment or the like. In short, it corresponds to sectionalconfiguration in which ultrafine irregularities with period of 20 to 100nm is added to the sectional configuration shown in FIG. 1(e). It wasconsidered that, if materials with a hard surface having suchthree-dimensional surface configuration with dual irregularities can beformed, it would create the highest tensile strength of adhesion. Theelectron microscopic photographs of the surface of two kinds of puretitanium pieces obtained through a new surface treatment method withtrial and error directed for forming the model are shown as FIG. 9-1(1,000 times), FIG. 9-2 (10,000 times) and FIG. 9-3 (100,000 times),respectively. The configuration in visage is the very FIG. 1(f) derivedsupposing to be such. With the piece formed through adhesion of pairedpieces according to NAT (test piece) using a one-part epoxy adhesive “EW2040” (made by Three M Japan Co. Ltd.: Main company in Tokyo, Japan),tensile strength of adhesion exhibited a level of 80 MPa.

Further, the electron microscopic photographs of the surface of α-βtitanium alloy pieces obtained through an analogous treatment method areshown as FIG. 10-1 (1,000 times), FIG. 10-2 (10,000 times) and FIG. 10-3(100,000 times). The configuration in visage is the very FIG. 1(h). Withthe piece formed through adhesion of paired pieces according to NAT(test piece) using “EW 2040”, tensile strength of adhesion exhibited 90to 100 MPa. On the other hand, the surface configuration shown in FIG.1(g) is depicted in a deskwork as expressing a new ideal configuration,considering “bar-like convex aggregate type” shown in FIG. 1(f). Furtherto say, while FIG. 1(f) shows “bar-like convex aggregate type”, anadverse situation is supposed such that concave portions are dominant.From this, a sectional configuration of “entangled U-shaped valley type”was presumed. However, such sectional configuration of materialssubjected to surface treatment has not been found yet.

The schematic view of the sectional configuration shown in FIG. 1(i) isone prepared by rewriting the standard configuration of the treatedmaterial according to NAT (actually only dimensions are defined) shownin FIG. 1(a) into an arranged form of a schematic view (sectionalconfiguration, etc.). That is, the schematic view of FIG. 1(i)corresponds to one in which ultrafine irregularities of 20 to 100 nmperiod are formed on a previously formed surface with neat concavebowl-like faces of 1.0 to 5 μm period (Rz). This configuration wasdepicted taking it as clarified that this configuration is possible fortitanium metals. This is viewed in FIG. 11-1 (1,000 times), FIG. 11-2(10,000 times) and FIG. 11-3 (100,000 times). Here, it is consideredthat possibility of obtaining this configuration for metal alloys otherthan titanium alloys is high.

FIG. 12-1 (10,000 times) and FIG. 12-2 (100,000 times) are electronmicroscopic photographs of surface of copper C1100 subjected to the newtreatment method according to this disclosure. FIG. 1(j) is a schematicsectional view depicting the strange surface configuration of this“specific copper type” subjected to treatment according to New NAT. Asshown in FIG. 1(j), the surface configuration presents a form in whichcubic or rectangular parallelepiped bodies with 10 to 200 nm sides ordisc-shaped bodies with about 200 nm diameter stand in a dispersedmanner. With the piece formed through adhesion of paired pieces of thematerial as shown in FIG. 12-1 and FIG. 12-2 treated according to NAT(test piece) using a one-part epoxy adhesive “EW 2040”, both shearstrength of adhesion and tensile strength of adhesion exhibited a levelof 80 MPa. However, it is presumed that tensile strength of adhesionwill be attained such as 90 to 100 MPa, if the small protrusions come toexist in further higher density.

FIG. 13-1 (1,000 times), FIG. 13-2 (10,000 times) and FIG. 13-3 (100,000times), which show strange surface configuration found when studying atreatment according to New NAT for copper C1100, are electronmicroscopic photographs depicting a situation in which numberlesswhiskers of copper oxide grow on a shaped article of copper. Thesectional configuration shown in FIG. 1(k) is a schematic view of thewhiskers of copper oxide. Whiskers, being long, cross among them and areentangled halfway of them. As to the configuration shown in FIG. 13-1 toFIG. 13-3, it is of a question whether adhesive can penetrate fully intothe root of the all whiskers even when “impregnation” of adhesive isperformed sufficiently.

In short, the question seems to occur because the whiskers are too long.Actually, with the piece formed through adhesion of paired pieces ofcopper C1100 shown in the electron microscopic photographs using theadhesive “EW 2040”, tensile strength of adhesion of 80 MPa cannot beattained, though shear strength of adhesion of 80 is attained. Here, itis presumed that, if the whiskers are shortened without changing theshape of densely growing whiskers to be of the shape of “densely growingwhiskers” shown in FIG. 1(k), tensile strength of adhesion of 90 to 100MPa will be attained. But sorry to say, the inventor has not succeededyet in forming copper pieces that have such presumed shortened whiskerslike a head with close cropped hairs.

The “sphere and whisker type” shown in FIG. 1(l) is a model of thesurface of magnesium alloy AZ31B subjected to treatment according toNAT. The “sphere and whisker type” is such a configuration that there isa surface with spherical concave-convex of 1 to 10 μm period, on whichfurther short whiskers seemingly of 50 to 100 nm diameter grow, in otherwords, short cropped hairs grow on the head. It is apparent, seeing theprecedent examples, that also this gives the best configuration.

(New NAT Theory as a Hypothesis Now)

Considering these sectional schematic views in such a manner, thesurface configuration, for which “tensile strength of adhesion” isexpected to be sufficiently high, is those shown in FIG. 1(b), FIG. 1(f)to FIG. 1(l) and this gives a gist of New NAT theory. As another gist,with a surface having such a configuration of fine irregularities and asurface layer of ceramic material such as metal oxide or metalphosphate, tensile strength of adhesion of the piece formed from pairedpartial pieces by adhesion is comparable with or somewhat higher thanshear strength of adhesion. Then, the idea consists in that, ifoperation of adhesion is carried out in a best mode according to New NATtheory, tensile strength of adhesion and shear strength of adhesion ofthe pieces formed from paired pieces by adhesion are substantiallycoincident with those of the cured adhesive that was used respectively.In short, in the case where the best adhesion is performed according toNew NAT theory, breaking stress by external force (strength of adhesion)of the pieces formed from paired partial pieces by adhesion is deemed tobe equal to the strength of the cured adhesive itself (for tensilestrength and shear strength), thus coming near to the simple theory ofmechanics of materials.

Here, two matters have not been verified by the New NAT theory. That is,the surface configurations shown in schematic views of FIG. 1(g) andFIG. 1(k) have not been verified yet. Further, in the case where aone-part epoxy adhesive, for example, “Scotch Weld EW2040” (made byThree M Japan Co. Ltd.: Main company in Tokyo, Japan) is used, tensilestrength of adhesion of 100 MPa is attained that seemed to be thehighest value as tensile strength of adhesion. The inventor formed anadhesive shaped as a dumbbell for measurement of tensile strength by apouring-molding method such that the “Scotch Weld EW2040” alone ispoured into a mold, and then made it cured. After it, the inventor triedto verify that the cured article provides a tensile strength near 100MPa causing it to be subjected to tensile strength test. But the trialwas reduced to a failure. The tensile strength merely comes up to 60 MPaat most, being unable to reduce generation of small voids insides of itto zero. Consequently, it has not been verified that the highest tensilestrength of adhesion of a piece formed of partial pieces throughadhesion amounts to the tensile strength of a cured adhesive itself.

It is interpreted that this was caused by not using an autoclave, whilegeneration of voids is restrained easily by a method using an autoclavewith which treatment is possible raising or reducing pressure. But, itis originally difficult to form a cured adhesive that is formed throughshaping an adhesive itself and is absolutely free of void. Although itis also considered that it is possible by injecting the adhesive into ametallic mold coated with TEFRON (polytetrafluoroethylene; trade mark),using an injection molding machine for thermosetting resin, suchexperiment will probably cause the injection molding machine to bespoiled. In short, verification is not sufficient in this respect.However, construed from data showing that the obtained tensile strengthof cured epoxy resin of about 100 MPa is the maximum among thoseprovided by manufacturers of macromolecular chemistry, it is understoodthat the above interpretation of the inventor is not wrong. The inventordid verify most of the New NAT hypothesis, which provides a method forobtaining an article with high strength formed of pieces comprising ametal or metals by adhesion, as a complete article formed of pieces byadhesion. In such a manner, the present disclosure is expected toprovide a new and excellent manufacturing method in the forthcomingindustries of general machines, medical instruments, electricalmachines, moving machines and other various kinds of machines.

Means for Solving the Problems

The present disclosure adopts the following means for solving theaforementioned problems.

The method for producing a metal containing composite according to afirst aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing metal shaped articles (M1) as adherends, each ofwhich, through various surface treatment, has a surface with ultrafineirregularities covered entirely with substantially ultrafine bowl-shapedconcaves of 20 to 100 nm diameter and in which said surface with saidultrafine irregularities is covered with a thin layer of ceramics suchas a metal oxide or a metal phosphate;

a step of painting the face for adhesion of each said metal shapedarticle (M1) with said adhesive (B) of a solvent containing type andvolatilizing the ketone solvent in a drying machine or throughair-drying; and

a step of causing one and another of said metal shaped articles (M1)which were painted with the one-part epoxy adhesive on the face foradhesion to abut on each other and fixing them, heating them at atemperature of 120 to 180° C. and curing the one-part adhesive toaccomplish adhesion,

wherein the tensile strength of adhesion between the metal shapedarticles is equal to or higher than the shear strength of adhesion.

The method for producing a metal containing composite according to asecond aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing metal shaped articles (M2) as adherends, each ofwhich, through various surface treatment, has a roughened surface, inwhich a forest of convexes shaped like thick walls or shapeless convexesas formed by collapse of such thick walls with long-short diameter of0.05 to 1 μm and height more than 0.3 μm stand with space 0.1 to 2 μmtherebetween, the roughened surface being entirely covered withultrafine irregularities having period of 20 to 100 nm and the wholesurface being covered with a thin layer of ceramics such as a metaloxide or a metal phosphate;

a step of painting the face for adhesion of each said metal shapedarticle (M2) with said adhesive (B) of a solvent containing type andvolatilizing the ketone solvent in a drying machine or throughair-drying; and

a step of causing one and another of said metal shaped articles (M2)which were painted with the one-part epoxy adhesive on the face foradhesion to abut on each other and fixing them, heating them at atemperature of 120 to 180° C. and curing the one-part adhesive toaccomplish adhesion,

wherein the tensile strength of adhesion between the metal shapedarticles is equal to or higher than the shear strength of adhesion.

The method for producing a metal containing composite according to athird aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing metal shaped articles (M3) as adherends, each ofwhich, through various surface treatment, has a roughened surface havingbowl-like concave faces of 1 to 5 μm period, the roughened surface beingentirely covered with ultrafine irregularities having period of 20 to100 nm and the whole surface being covered with a thin layer of ceramicssuch as a metal oxide or a metal phosphate;

a step of painting the face for adhesion of each said metal shapedarticle (M3) with said adhesive (B) of a solvent containing type andvolatilizing the ketone solvent in a drying machine or throughair-drying; and

a step of causing one and another of said metal shaped articles (M3)which were painted with the one-part epoxy adhesive on the face foradhesion to abut on each other and fixing them, heating them at atemperature of 120 to 180° C. and curing the one-part adhesive toaccomplish adhesion,

wherein the tensile strength of adhesion between the metal shapedarticles is equal to or higher than the shear strength of adhesion.

The method for producing a metal containing composite according to afourth aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing metal shaped articles (M4) as adherends, each ofwhich, through various surface treatment, has a surface with ultrafineirregularities covered entirely with cubic protrusions in a dimension of10 to 200 nm or mixed protrusions of such cubic protrusions anddisc-shaped protrusions of 100 to 250 nm diameter standing on a plain ina density of 5 to 50 per square of 200 nm side, the whole surface beingcovered with a thin layer of ceramics such as a metal oxide or a metalphosphate;

a step of painting the face for adhesion of each said metal shapedarticle (M4) with said adhesive (B) of a solvent containing type andvolatilizing the ketone solvent in a drying machine or throughair-drying; and

a step of causing one and another of said metal shaped articles (M4)which were painted with the one-part epoxy adhesive on the face foradhesion to abut on each other and fixing them with a jig, heating themat a temperature of 120 to 180° C. and curing the one-part adhesive toaccomplish adhesion,

wherein the tensile strength of adhesion between the metal shapedarticles is equal to or higher than the shear strength of adhesion.

The method for producing a metal containing composite according to afifth aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing metal shaped articles (M5) as adherends, each ofwhich, through various surface treatment, has a surface configurationloaded with spherical entities of about 100 nm diameter combined amongthemselves along with a configuration of numerous short whiskers below10 nm growing on the surface of the spherical entities, the wholesurface being covered with a thin layer of ceramics such as a metaloxide or a metal phosphate;

a step of painting the face for adhesion of each said metal shapedarticle (M5) with said adhesive (B) of a solvent containing type andvolatilizing the ketone solvent in a drying machine or throughair-drying; and

a step of causing one and another of said metal shaped articles (M5)which were painted with the one-part epoxy adhesive on the face foradhesion to abut on each other and fixing them, heating them at atemperature of 120 to 180° C. and curing the one-part adhesive toaccomplish adhesion,

wherein the tensile strength of adhesion between the metal shapedarticles is equal to or higher than the shear strength of adhesion.

The method for producing a metal containing composite according to asixth aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing two kinds of metal shaped articles as adherendsselected from the following five kinds of metal shaped articles (M1 toM5):

a metal shaped article (M1), which, through various surface treatment,has a surface with ultrafine irregularities covered entirely withsubstantially ultrafine bowl-shaped concaves of 20 to 100 nm diameterand in which said surface with said ultrafine irregularities is coveredwith a thin layer of ceramics such as a metal oxide or a metalphosphate,

a metal shaped article (M2), which, through various surface treatment,has a roughened surface, in which a forest of convexes shaped like thickwalls or shapeless convexes as formed by collapse of such thick wallswith long-short diameter of 0.05 to 1 μm and height more than 0.3 μmstand with space 0.1 to 2 μm therebetween, the roughened surface beingentirely covered with ultrafine irregularities having period of 20 to100 nm and the whole surface being covered with a thin layer of ceramicssuch as a metal oxide or a metal phosphate,

a metal shaped article (M3), which, through various surface treatment,has a roughened surface having bowl-like concave faces of 1 to 5 μmperiod, the roughened surface being entirely covered with ultrafineirregularities having period of 20 to 100 nm and the whole surface beingcovered with a thin layer of ceramics such as a metal oxide or a metalphosphate,

a metal shaped article (M4), which, through various surface treatment,has a surface with ultrafine irregularities covered entirely with cubicprotrusions in a dimension of 10 to 200 nm or mixed protrusions of suchcubic protrusions and disc-shaped protrusions of 100 to 250 nm diameterstanding on a plain in a density of 5 to 50 per square of 200 nm side,the whole surface being covered with a thin layer of ceramics such as ametal oxide or a metal phosphate, and

a metal shaped article (M5), which, through various surface treatment,has a surface configuration loaded with spherical entities of about 100nm diameter combined among themselves along with a configuration ofnumerous short whiskers below 10 nm growing on the surface of thespherical entities, the whole surface being covered with a thin layer ofceramics such as a metal oxide or a metal phosphate;

a step of painting the face for adhesion of each said selected metalshaped article (M1 to M5) with said adhesive (B) of a solvent containingtype and volatilizing the ketone solvent in a drying machine or throughair-drying; and

a step of causing one and another of said selected metal shaped articles(M1 to M5) which were painted with the one-part epoxy adhesive on theface for adhesion to abut on each other and fixing them, heating them ata temperature of 120 to 180° C. and curing the one-part adhesive toaccomplish adhesion,

wherein the tensile strength of adhesion between the metal shapedarticles is equal to or higher than the shear strength of adhesion.

The method for producing a metal containing composite according to aseventh aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing one kind of metal shaped article as an adherendselected from the following five kinds of metal shaped articles (M1 toM5):

a metal shaped article (M1), which, through various surface treatment,has a surface with ultrafine irregularities covered entirely withsubstantially ultrafine bowl-shaped concaves of 20 to 100 nm diameterand in which said surface with said ultrafine irregularities is coveredwith a thin layer of ceramics such as a metal oxide or a metalphosphate,

a metal shaped article (M2), which, through various surface treatment,has a roughened surface, in which a forest of convexes shaped like thickwalls or shapeless convexes as formed by collapse of such thick wallswith long-short diameter of 0.05 to 1 μm and height more than 0.3 μmstand with space 0.1 to 2 μm therebetween, the roughened surface beingentirely covered with ultrafine irregularities having period of 20 to100 nm and the whole surface being covered with a thin layer of ceramicssuch as a metal oxide or a metal phosphate,

a metal shaped article (M3), which, through various surface treatment,has a roughened surface having bowl-like concave faces of 1 to 5 μmperiod, the roughened surface being entirely covered with ultrafineirregularities having period of 20 to 100 nm and the whole surface beingcovered with a thin layer of ceramics such as a metal oxide or a metalphosphate,

a metal shaped article (M4), which, through various surface treatment,has a surface with ultrafine irregularities covered entirely with cubicprotrusions in a dimension of 10 to 200 nm or mixed protrusions of suchcubic protrusions and disc-shaped protrusions of 100 to 250 nm diameterstanding on a plain in a density of 5 to 50 per square of 200 nm side,the whole surface being covered with a thin layer of ceramics such as ametal oxide or a metal phosphate, and

a metal shaped article (M5), which, through various surface treatment,has a surface configuration loaded with spherical entities of about 100nm diameter combined among themselves along with a configuration ofnumerous short whiskers below 10 nm growing on the surface of thespherical entities, the whole surface being covered with a thin layer ofceramics such as a metal oxide or a metal phosphate;

a step of painting the face for adhesion of said selected metal shapedarticle (M1 to M5) with said adhesive (B) of a solvent containing typeand volatilizing the ketone solvent in a drying machine or throughair-drying;

a step of preparing a resin shaped article (P1) as another adherend bycuring a thermosetting epoxy resin composition comprising an epoxy resinas a main constituent;

a step of forming a roughened face for adhesion of the resin shapedarticle (P1) with several decades m order on a specified portion of saidresin shaped article (P1) by grinding it with physical means, cleaningwith water, drying and removing dirt;

a step of painting the roughened face for adhesion of said resin shapedarticle (P1) with said adhesive (B) of a solvent containing type andvolatilizing the ketone solvent in a drying machine or throughair-drying;

a step of causing the face for adhesion of said selected metal shapedarticle (M1 to M5) and the roughened face of adhesion of said resinshaped article (P1), both of which were painted with the one-part epoxyadhesive to abut on each other and fixing the metal shaped article andthe resin shaped article, heating the fixed shaped articles at atemperature of 150 to 180° C. and curing the one-part adhesive toaccomplish adhesion,

wherein the tensile strength of adhesion between the metal shapedarticle and the resin shaped article is equal to or higher than theshear strength of adhesion.

The method for producing a metal containing composite according to aneighth aspect of the present disclosure comprises:

a step of preparing an adhesive (B) of a solvent containing type formedas a suspension of low viscosity by adding a ketone solvent to aone-part epoxy adhesive of a dicyandiamide-curable type (A) and mixingthe same;

a step of preparing one kind of metal shaped article as an adherendselected from the following five kinds of metal shaped articles (M1 toM5):

a metal shaped article (M1), which, through various surface treatment,has a surface with ultrafine irregularities covered entirely withsubstantially ultrafine bowl-shaped concaves of 20 to 100 nm diameterand in which said surface with said ultrafine irregularities is coveredwith a thin layer of ceramics such as a metal oxide or a metalphosphate,

a metal shaped article (M2), which, through various surface treatment,has a roughened surface, in which a forest of convexes shaped like thickwalls or shapeless convexes as formed by collapse of such thick wallswith long-short diameter of 0.05 to 1 μm and height more than 0.3 μmstand with space 0.1 to 2 μm therebetween, the roughened surface beingentirely covered with ultrafine irregularities having period of 20 to100 nm and the whole surface being covered with a thin layer of ceramicssuch as a metal oxide or a metal phosphate,

a metal shaped article (M3), which, through various surface treatment,has a roughened surface having bowl-like concave faces of 1 to 5 μmperiod, the roughened surface being entirely covered with ultrafineirregularities having period of 20 to 100 nm and the whole surface beingcovered with a thin layer of ceramics such as a metal oxide or a metalphosphate,

a metal shaped article (M4), which, through various surface treatment,has a surface with ultrafine irregularities covered entirely with cubicprotrusions in a dimension of 10 to 200 nm or mixed protrusions of suchcubic protrusions and disc-shaped protrusions of 100 to 250 nm diameterstanding on a plain in a density of 5 to 50 per square of 200 nm side,the whole surface being covered with a thin layer of ceramics such as ametal oxide or a metal phosphate, and

a metal shaped article (M5), which, through various surface treatment,has a surface configuration loaded with spherical entities of about 100nm diameter combined among themselves along with a configuration ofnumerous short whiskers below 10 nm growing on the surface of thespherical entities, the whole surface being covered with a thin layer ofceramics such as a metal oxide or a metal phosphate;

a step of painting the face for adhesion of said selected metal shapedarticle (M1 to M5) with said adhesive (B) of a solvent containing typeand volatilizing the ketone solvent in a drying machine or throughair-drying;

a step of preparing a prepreg as a resin shaped article (P2) made ofthermosetting epoxy resin composition containing reinforcing fibers asanother adherend;

a step of preparing a jig for shaping adapted for containing saidprepreg (P2) and said selected one kind of metal shaped article (M1 toM5); and

a step of loading said prepreg (P2) and said one kind of metal shapedarticle (M1 to M5) in said jig, fastening said jig, placing said jigwith said prepreg (P2) and metal shaped article (M1 to M5) in a heatingcontainer such as an autoclave and curing the entire epoxy resin partwith determined operation to accomplish adhesion of the resin shapedarticle (P2) containing reinforcing fibers that has been cured as aresult and the metal shaped article (M1 to M5),

wherein the tensile strength of adhesion between the metal shapedarticle and the resin shaped article is equal to or higher than theshear strength of adhesion.

The method for producing a metal containing composite according to ninthaspect of the present disclosure is characterized in that, in any one offirst to eighth aspects, said ketone solvent is methyl-isobutyl-ketone.

The metal containing composite produced according to a tenth aspect ofthe present disclosure is a metal containing composite produced by themethod for producing a metal containing composite according to any oneof first to ninth aspects;

wherein said first metal shaped article (M1) is of aluminum, of aluminumalloy or aluminum-plated steel sheet, said second metal shaped article(M2) and said third metal shaped article (M3) are of first to fourthspecies of pure titanium or titanium alloy, said fourth metal shapedarticle (M4) is of copper or of copper alloy, and said fifth metalshaped article (M5) is of magnesium alloy.

Advantageous Features of the Disclosure

The present disclosure clarified ideal sectional surface configurationof metal materials for obtaining high shear strength of adhesion andtensile strength of adhesion for the adhesion of pieces comprising ametal or metals with a one-part epoxy adhesive according to New NATtheory, and further clarified the method for forming such surfaceconfiguration of a metal. At the same time, the disclosure clarified themaximum tensile strength of adhesion is substantially same as thetensile strength of the one-part epoxy adhesive itself. Consequently,complete adhesion or adhesion for all directions becomes possible withthe present disclosure, and also the direction of study is shown here soas to make the strength of adhesion be of the maximum level if obtainedstrength of adhesion does not come to the level. In short, the presentdisclosure gives reliability as to what a strength level of adhesionjoined with an adhesive can exhibit, whether it is adapted to practicaluse or not, or the like. As a result, it becomes possible to provide anew manufacturing method in the forthcoming industries of generalmachines, medical instruments, electrical machines, moving machines andother various kinds of machines.

BRIEF EXPLANATION OF DRAWINGS

FIG. 1(a) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part as “treated according to NAT” in the face of adhesion withcured adhesive in section.

FIG. 1(b) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “ultrafine concaves of bowl shape” in the face of adhesionwith cured adhesive in section.

FIG. 1(c) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “V-shaped valley type” in the face of adhesion with curedadhesive in section.

FIG. 1(d) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “step-like shape” in the face of adhesion with curedadhesive in section.

FIG. 1(e) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “shape of mountains on a plain” in the face of adhesionwith cured adhesive in section.

FIG. 1(f) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “bar-like convex aggregate type” as an ideal type I in theface of adhesion with cured adhesive in section.

FIG. 1(g) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “entangled U-shaped valley type” as an ideal type II inthe face of adhesion with cured adhesive in section.

FIG. 1(h) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “random type” as an ideal type III in the face of adhesionwith cured adhesive in section.

FIG. 1(i) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “standard type” as an ideal type IV in the face ofadhesion with cured adhesive in section.

FIG. 1(j) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “specific copper type” in the face of adhesion with curedadhesive in section.

FIG. 1(k) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “densely growing whisker type” in the face of adhesionwith cured adhesive in section.

FIG. 1(l) is a sectional schematic view for explaining the principle ofthe present disclosure and for showing surface configuration of themetal part of “sphere and whisker type” in the face of adhesion withcured adhesive in section.

FIG. 2 is a perspective view showing a test piece formed by adhesion ofpartial pieces, of two metal pieces or of a metal piece and a CFRPpiece, with an adhesive for measuring shear strength of adhesion fromthe breaking force at breaking by pulling out the test piece.

FIG. 3 is a perspective view showing a test piece formed by adhesion ofpartial pieces, of two metal pieces or of a metal piece and a CFRPpiece, with an adhesive for measuring tensile strength of adhesion fromthe breaking force at breaking by pulling out the test piece.

FIG. 4 is electron microscopic photographs of an Al-alloy material A7075treated according to NAT with magnification of 10,000 times and 100,000times respectively.

FIG. 5 is an electron microscopic photograph of an Al-alloy materialA7075 treated according to New NAT with magnification of 100,000 times.

FIG. 6 is electron microscopic photographs of a stainless steel materialSUS304 material treated according to NAT with magnification of 10,000times and 100,000 times respectively.

FIG. 7 is electron microscopic photographs of a ferrous material SPCCtreated according to NAT with magnification of 10,000 times and 100,000times respectively.

FIG. 8 is electron microscopic photographs of first species of puretitanium material “KS40” (made by Kobe-seikousho Co. Ltd. At Kobe. HyogoPref., Japan) treated according to NAT with magnification of 10,000times and 100,000 times respectively.

FIG. 9-1 to FIG. 9-3 are electron microscopic photographs of secondspecies of pure titanium material “TP340H” (made by ShinnittetsusumikinCo. Ltd. at Tokyo, Japan) treated according to New NAT withmagnification of 1,000 times (FIG. 9-1), 10,000 times (FIG. 9-2) and100,000 times (FIG. 9-3) respectively.

FIG. 10-1 to FIG. 10-3 are electron microscopic photographs of an α-βtitanium alloy material “KSTI-9” (made by Kobe-seikousho Co. Ltd. AtKobe. Hyogo Pref., Japan) treated according to New NAT withmagnification of 1,000 times (FIG. 10-1) 10,000 times (FIG. 10-2) and100,000 times (FIG. 10-3) respectively.

FIG. 11-1 to FIG. 11-3 are electron microscopic photographs of an α-βtitanium alloy material “KS6-4” (made by Kobe-seikousho Co. Ltd. AtKobe. Hyogo Pref., Japan) treated according to New NAT withmagnification of 1,000 times (FIG. 11-1), 10,000 times (FIG. 11-2) and100,000 times (FIG. 11-3) respectively.

FIG. 12-1 to FIG. 12-2 are electron microscopic photographs of a toughpitch copper material “C1100” treated according to New NAT withmagnification of 10,000 times (FIG. 12-1) and 100,000 times (FIG. 12-2)respectively.

FIG. 13-1 to FIG. 13-3 are electron microscopic photographs of a toughpitch copper material “C1100” treated according to New NAT withmagnification of 1,000 times (FIG. 13-1), 10,000 times (FIG. 13-2) and100,000 times (FIG. 13-3) respectively.

FIG. 14 is an electron microscopic photograph of a magnesium alloymaterial AZ31B treated according to NAT with magnification of 100,000times.

FIG. 15 is a view showing a visage of a CFRP piece used as a test piecepartially cut away along with the direction of arrangement of carbonfibers in it.

FIG. 16 is a view showing a visage of a test piece for measuring tensilestrength of adhesion between a metal partial piece and a CFRP partialpiece formed of the two partial pieces by adhesion.

FIG. 17 is a view showing a visage of another test piece for measuringtensile strength of adhesion between a metal partial piece and a CFRPpartial piece formed of the two partial pieces by adhesion.

FIG. 18 is a schematic view showing one of two kinds of directions oflamination of carbon fiber bundles in a CFRP partial piece in the casewhere the test piece in the form shown in FIG. 17 is fabricated.

FIG. 19 is a schematic view showing the other of two kinds of directionsof lamination of carbon fiber bundles in a CFRP partial piece in thecase where the test piece in the form shown in FIG. 17 is fabricated.

FIG. 20 is a photograph showing a visage of a test piece comprising twopartial pieces of “Al-alloy A7075” for measuring tensile strength ofadhesion in which a photograph of the partial pieces after test weretaken in an arranged manner.

FIG. 21 is an enlarged photograph of respective faces of adhesion of thetest piece shown in FIG. 20.

DETAILED EXPLANATION OF EMBODIMENTS

(1) Various Metals and Chemical Treatment Thereof (Treatment Accordingto New NAT)

“Treatment according to New NAT” referred to in the present disclosureissues from the treatment method provided in the aforementioned NATtheory. The surface configuration of the materials treated according toNew NAT includes configuration that does not necessarily require thecondition “(1) the metal material has a roughened surface withconvex-concave roughness of 0.8 to 10 μm (Rz) period (roughened surfaceof micron order period)” as one of the five conditions in theaforementioned treatment according to NAT. Then, the surfaceconfiguration formed through the treatment according to New NAT isdefined as “a surface treated according to New NAT” and the method forforming the surface is defined as “treatment according to New NAT”. Thedifference of “a surface treated according to New NAT” from a surfacetreated according to previous NAT consists in that the former does notactually require the first condition of NAT “the metal material has aroughened surface with convex-concave roughness of 0.8 to 10 μm (Rz)period (roughened surface of micron order period)”. Further, thecondition of NAT such that “(2) there is fine irregularities of 10 to300 nm period on the above roughened surface” provided on theprerequisite condition (1) is also hard to say as a required condition.Rather, having shown that all examples of more concrete surfaceconfiguration with fine irregularities, the surface configuration itselfbecomes a required condition.

To say about FIG. 1, the inventor supposes that the surfaceconfigurations shown in FIG. 1(b), FIG. 1(j), FIG. 1(k) and FIG. 1(l) donot require the surface to be a roughened surface of micron order. It isalso considered that such surface configuration with a slackconvex-concave of several μm period as shown in FIG. 1(b) happened to beformed when endeavors were made for causing the existing metal alloys tocome nearer to be of such configuration. Further, the sectionalconfiguration shown in FIG. 1(f) to FIG. 1(h) is supposed to be of veryviolently roughened surfaces of 0.1 to several μm period withoutregularity and a surface with ultrafine irregularities of 20 to 100 nmperiod is overlaid on this. This is of a shape quite different from theimage of the dual irregularities in the condition according to NAT theinventor had estimated beforehand. Consequently, it can be said, in adirect expression, that the surface configuration required by “New NAT”according to the present disclosure is one that approximates to theschematic views shown in FIG. 1(b) and FIG. 1(f) to FIG. 1(l). As therequired condition other than these, the condition such that the surfaceis covered with a ceramics such as metal oxide or metal phosphate is thesame as one according to NAT.

(Metal Species Allowable for Use)

Substantially all of hard metal species can be used in the presentdisclosure. The present disclosure merely defines surface configurationof used metals and such usable metals include all species as long asthey are hard metals. However, when metal species or metal alloy specieshave been selected arbitrarily, it would not be considered possible tomake the surface configuration of all of the metal species or metalalloy species have surface configurations similar to those shown in FIG.1(b), FIG. 1(f) to FIG. 1(l), even if it were tried. Even in trial anderror, these ideal surface configurations could not been attained. Thereason is such that some shaped articles with ultrafine irregularitiesgiving a basis of the shown configuration were actually obtained forsome metal species or metal alloy species through experiment andobservation or were thought to be obtained. The shown schematic views ofsurface configuration were prepared presuming that the ideal sectionalconfiguration for securing sufficient strength of adhesion would be suchas these shown. That is, most of these were such as ones taken as modelsor ones depicted based on the experiences by the inventor. Only “randomtype” shown in FIG. 1(h) is depicted as a desk work.

As explained above, the configuration shown in FIG. 1(b) comes fromexamples of Al-alloy, the configuration shown in FIG. 1(f) comes fromexamples of pure titanium, the configurations shown in FIG. 1(g) andFIG. 1(i) come from examples of titanium alloy, the configurations shownin FIG. 1(j) and FIG. 1(k) come from examples of copper and theconfiguration shown in FIG. 1(l) comes from examples of Mg-alloy.Consequently, the configuration shown in FIG. 1(b) is possible to beaimed at, if the used material is Al-alloy. However, it seems difficult,if other metal species are used. The configuration shown in FIG. 1(f) ispossible if pure titanium is used, and the configurations shown in FIG.1(f) and FIG. 1(i) are possible if titanium alloy is used. Theconfigurations shown in FIG. 1(j) and FIG. 1(k) are possible if copperis used, and the configuration shown in FIG. 1(l) is possible ifMg-alloy is used. Further, what is possible for all metal species is“the standard type” as an ideal type IV shown in FIG. 1(i).

The base of the standard procedures of treatment according to NATdisclosed in the Patent Documents 1 to 9 comprises four steps of (1)degreasing, (2) chemical etching, (3) fine etching and (4) surfacehardening. Here, there are metal species with which the above fineetching and surface hardening can be performed simultaneously bychemical etching alone. On the other hand, there are cases in whichdevelopment of treatment method must be given up without succeeding infine etching of some metal species. Even in such cases, there are alsomany cases in which everything goes well by performing the surfacehardening step beforehand when the fine etching has been taken asdifficult. In short, the procedures involve all of unprecedentedoperations, most of which were clarified through trial and error withoutsecure theoretical background and have not yet come to be explained bycombination of simple methods.

(2) Epoxy Adhesives

The adhesive used in the present disclosure is a one-part epoxy adhesiveand most of ones commercially available in common can be used. When thecomposite piece formed by adhesion of a metal piece subjected totreatment according to NAT or New NAT and another adherend piece by useof the adhesion method described later (referred to as “NAT adhesionmethod” below) was broken by pulling out the composite piece and itsshear strength of adhesion is measured, the shear strength of adhesionunder an ordinary temperature was within a range of 60 to 80 MPa formost of commercially available adhesives, and in most cases it was nearto 70 MPa. In short, the strength of adhesion under an ordinarytemperature does not exhibit so much variation among commerciallyavailable one-part adhesives and the strength with same adhesive usedhardly depends on metal species or metal alloy species. Here, theone-part thermosetting epoxy adhesives the inventor et. al. usually useare “EP106NL” (made by Cemedine Co. Ltd, Main company in Tokyo, Japan)and “Scotch Weld EW2040” (made by Three M Japan Co. Ltd.: Main companyin Tokyo, Japan), both of which are of dicyandiamide-curable type.

Here, use of the above “EW2040” is preferable, if not only the strengthof adhesion under an ordinary temperature but also the strength ofadhesion under a high temperature, for example, of 150° C. is important.That is, using this adhesive in NAT adhesion of two pieces of Al-alloyA7075 subjected to treatment according to NAT, shear strength of 35 MPaunder 150° C. was recorded. The adhesive that has the highest strengthof adhesion under 150° C. is a one-part epoxy adhesive prepared by theinventor (Patent Document 10), which exhibited about 45 MPa. However, asmarket of this field has not been formed yet, the inventor does notproduce this adhesive now.

(3) Operation of Adhesion

While an “operation of impregnation” is necessary in NAT adhesionmethod, this is similar for the New NAT method according to the presentdisclosure. The “operation of impregnation” is an operation of allowingan adhesive to penetrate into the ultrafine concaves on the surface ofthe metal piece by intentionally lowering viscosity of the one-partepoxy adhesive that is viscous in an ordinary temperature. Specifically,there are two ways of (a) using a closed container, and (b) using aketone solvent, as following.

(a) Using a Closed Container

The required portion of each of metal pieces is painted with anadhesive, after which the metal pieces are placed in a desiccator heatedto 50 to 70° C. preliminarily and the pressure in the desiccator isreduced with a vacuum pump. After pressure reduction is performed forseveral minutes, air is introduced to resume the ordinary pressure.After then, pressure is reduced again. Thus, operation of pressurereduction/resumption to ordinary pressure is repeated several times,after which the metal pieces are taken out of the desiccator. Theadhesive, which is paste-like originally, apparently has once come to bein a liquid state. Then, joining one metal piece with adhesive coatedwith another, the face of adhesion is fixed using a clip, a vice, or thelike and the paired pieces are placed in a hot air drying machine assuch for a curing step.

(b) Using a Ketone Solvent

The above method (a) requires extremely large bags, autoclaves, or thelike, if metal pieces are of a large scale, thus making it difficult toperforming the method in a commercial manner. This method of using abath liquid of a ketone is devised in such a circumstances and is veryefficient, although it is only applicable to the case where the usedadhesives are ones of one-part epoxy adhesives of adicyandiamide-curable type. Here, as most of commercially availableone-part epoxy adhesives are of a dicyandiamide-curable type, almost allof them actually can be used (Patent Documents 11 and 12). Specificmanners of the method using a bath liquid of a ketone are as follows.

At first, a small amount of methyl-isobutyl-ketone (MIBK) is added to aone-part adhesive, which is then mixed well to become a suspension withlow viscosity. The required portion of each of metal pieces is paintedwith the above suspension and then the metal pieces are placed in a warmair drying machine for about 20 minutes to cause the solvent to bevolatilized completely. This is a step of “impregnation treatment”. This“impregnation treatment” by use of MIBK has importance in the presentdisclosure, the reason of which is such that the treatment is practicaland also impregnation is performed more securely than the method using aclosed container. Here, the key point of secure impregnation consists ina solvent volatilization step with a warm air drying machine and insecuring sufficient time for drying with sufficient ventilation in thedrying machine. Further, if the adhesive on a metal piece is taken asthin and little, then the metal piece is additionally painted with theoriginal adhesive to be thicker. After then, one metal piece withadhesive painted thereon is caused to abut closely on another metalpiece with adhesive painted thereon and the paired piece, having beenfixed with small fixing jig, is placed in a hot air drying machine for acuring step.

(Heat Curing and Procedure Against Flowing Away)

A common curing method is used as one for curing a one-part epoxyadhesive. That is, a standard curing procedure is such that a hot airdrying machine is set at a temperature of 120 to 135° C., then pairedmetal pieces fixed by clip, etc., are placed in the hot air dryingmachine, temperature is raised by immediately setting the temperature of170° C., the situation is kept for 20 minutes after the temperatureattained 170° C., and then curing operation ends. Here, actual operationof adhesion requires various techniques and skills.

In the case of adhesion of large scale articles, techniques, skills anddevices are required as to what thickness of an adhesive layer issuitable, whether there are concave-convex in the gap space on the faceof adhesion where adhesive can exist or not, whether adhesive that hasmelt and become liquidized flows away from the face of adhesion and ismissed or not, or the like. In short, as even an adhesive with highviscosity once becomes liquid-like at a temperature of 60 to 90° C.,such cases occur frequently that the adhesive flows away from the placewhere to be solidified and the operation ends in a failure.Consequently, it is necessary to surround the circumference of the faceof adhesion with a TEFRON tape in a fastened state. Further, it isimportant also to apply the adhesive in surplus on the face of adhesionbeforehand, supposing decrease of adhesive on the face of adhesion byflowing out of somewhat adhesive.

The operation of winding and fastening the TEFRON tape for sealing offadhesive is effective in a case where the distance between the pair ofmetal pieces (test pieces) cannot be small with a complementary jig,that is, the thickness of the adhesive layer to be cured cannot berestrained within 0.1 to 0.3 mm. In other words, the TEFRON tape isuseful in the case where the adhesive layer cannot help being thick.This is because adhesive itself expands during heat curing with theadhesive sealed under pressure and inner pressure increases due to theconfined state, thus restraining voids, which are formed by evaporationof certain impurities, a tiny amount of water, etc., from beinggenerated within the cured entity, rather than it is aimed at procedureagainst flowing away. Consequently, in order to form an adhesive layerwithout voids, a preliminary working operation is important such that atleast the surfaces of the paired metal pieces to be joined by adhesionare flattened to have no irregularities with a milling machine or thelike and the gap between the paired metal pieces are made as small aspossible when the faces with adhesive applied on have been caused toabut on each other.

The one-part epoxy adhesive used in the present disclosure is subjectedto “impregnation treatment” as explained above. In this, when a pair ofmetal pieces that have been painted with adhesive are caused to abut andfixed, there is a way of sandwiching a film-shaped epoxy adhesivebetween the metal pieces. This is a method in which the one-part epoxyadhesive according to the present disclosure is used as a primer and afilm-shaped adhesive laminated on it is used as a main adhesive. Suchfilm-shaped adhesives are used frequently that are formed byimpregnating a nonwoven fabric of nylon or the like with one-part epoxyadhesive. Here, the nonwoven fabric prevents the adhesive ingredientfrom flowing away in curing under raised temperature and the reinforcingfiber serves for solving the problem such that strength of the curedentity in adherend is lowered due to generation of voids. Consequently,it can be used also in the present disclosure.

Here, when the two metal pieces were joined by adhesion with acommercially available film-shaped adhesive, most of which are specifiedfor aircrafts made in USA, sandwiched between the metal pieces, thestrength of adhesion is lowered, as compared with the strength ofadhesion of the metal pieces joined by use of a one-part epoxy adhesive“Scotch Weld EW2040” alone, according to the experiment performed by theinventor. While this is a result regarding currently availablefilm-shaped adhesives, commercially available film-shaped adhesives willbe changed to have high performance, if the present disclosure comes tobe widely applied to moving machine manufacturing industry. To sayregarding this, the strength of adhesion before NAT theory proposed bythe inventor was at most 30 to 40 MPa and there was not a standardmethod for measuring strength of adhesion higher than 40 MPa.Consequently, if existence of strength of adhesion far higher than thisis clarified by dissemination of NAT theory and the present disclosure,new development by adhesive manufacturers will begin. In short, sayingat present, the method of using a film-shaped adhesive is superior inoperation against flowing away of adhesive. While strength of adhesionitself decreases by sandwiching a film-shaped adhesive, this can beimproved conveniently.

(Method for Adhesion of a Metal Piece and a CFRP Piece)

When a CFRP piece that has been already shaped and cured is used as oneof pieces to be joined by adhesion, the portion of adhesion is groundwith a sand-paper, etc., preferably to an extent that a part of CF isexposed. It is preferable that the CFRP piece after having been groundis immersed in a resin bath, rinsed with water to get rid of dirt andthen dried in a hot air drying machine. After then it is also preferableto perform “impregnation treatment” in a similar manner as in the aboveoperation of adhesion of metal pieces. A CFRP piece with adhesivepainted thereon is formed through the operation. After then, this CFRPpiece and a metal with adhesive painted thereon are caused to abut oneach other, fixed by use of a jig for adhesion, etc., and placed in ahot air drying machine to cause adhesive to be cured, in a similarmanner as described above.

On the other hand, in the case where the adherend to be joined with ametal piece by adhesion is a CFRP prepreg composite, there is nooperation to be performed on the side of CFRP. The metal piece withadhesive painted thereon obtained through the above operation is placedon the designated position of a prepreg composite placed in a mold andthe mold is fastened. Then, the mold with the metal piece and prepregcomposite therein is placed in an autoclave and a predeterminedoperation of curing CFRP is performed. Here, as among CFRP prepregsthere are some that are of a type cured at a low temperature of 130° C.,it is preferable to raise the temperature up to 170° C. even for a testpiece in which such a CFRP prepreg is used and keep the situation atleast 15 minutes.

(4) Cured Entity of Thermoplastic Epoxy Resin Composition

In order to measure the strength of adhesion of test piece formed byjoining paired metal pieces subjected to NAT treatment with adhesive, atest piece comprising paired metal pieces joined by adhesion with aone-part epoxy adhesive were broken through pulling off in test toobtain strength of adhesion. The strength of adhesion obtained here isone between the metal pieces and also one between each metal piece andthe cured adhesive. On the other hand, the strength of adhesion obtainedat tensile breaking of a test piece joined by adhesion of a metal piecesubjected to NAT treatment and a CFRP piece is one between the metalpiece and CFRP piece. At the same time, this strength of adhesion isalso one between the cured adhesive and CF. Further to say, this is onebetween the matrix resin within the cured adhesive and CF. The reason isas explained above.

In short, the strength of adhesion between CF and matrix resin (that isalso a thermosetting epoxy resin composition) remains currently in alevel of about 40 MPa. Improvement of strength of adhesion between thematrix resin within CFRP and CF remains in a limit such that thestrength is raised to about 60 MPa by use of a conventional type of CFhaving a large surface area.

However, some different reinforcing fibers beside CF may further appearin future and the strength of adhesion between CF and cured epoxy resinas a matrix resin may become comparable to the tensile strength of thecured epoxy resin itself with improvement in surface treatment method ofCF. In such a case, the strength of adhesion of a piece obtained byadhesion according to NAT of paired pieces of the CFRP with a one-partepoxy adhesive may have the same value of shear strength or tensilestrength of the one-part epoxy adhesive itself. Anyway, the highestshear strength of adhesion and the highest tensile strength of adhesionthat the piece (test piece) formed by adhesion of paired pieces attainscannot be beyond the shear strength and tensile strength of the curedone-part epoxy adhesive itself respectively.

(Tensile Strength of Cured Adhesive)

Even if the adherend is a metal piece subjected to New NAT treatmentaccording to the present disclosure, the shear strength of adhesion andtensile strength of adhesion of the piece formed by adhesion accordingto NAT of the metal pieces cannot be beyond the shear strength andtensile strength of the cured one-part epoxy adhesive itselfrespectively. Consequently, it is important to obtain shear strength andtensile strength of a cured adhesive beforehand and to know to what anextent metal adhesion techniques have approximated the ideal values orthe highest values.

Although the inventor et al. performed experiments in many times forobtaining the tensile strength of the cured commercially availableadhesives “EP106NL” and “EW2040” themselves as on-part epoxy adhesives,all of them resulted in failure. Preparing a shaped article of adhesivein a method by pouring into a mold was tried in which a mold coated withTEFRON is formed and then loaded with adhesive therein. But the preparedshaped article for measuring tensile strength exhibited 60 MPa at mostand small voids were generated even in the shaped article with thehighest tensile strength. The mold that has been loaded with adhesivewas placed in a hot state desiccator and operation of pressure reductionby a vacuum pump and resumption to ordinary pressure with addition ofair was repeated (that is, operation similar to “impregnation treatment”was performed), the mold loaded with adhesive was taken out of thedesiccator, a lid was placed on the mold and fixed by a jig with theadhesive partially spilt and the mold was placed in a hot air dryingmachine to be cured. Nevertheless, generation of small voids could notbe prevented.

Therefore, it was considered that samples appreciated as usable formeasurement of tensile strength could not be prepared without performingthe curing in an autoclave method in a similar manner as when CFRPprepreg is cured. Although this operation is required for verifying NewNAT theory, it is regrettably not necessarily required for verifyingeffectiveness of the present disclosure. Thus, the inventor gave it upfrom the standpoint of an engineer in a firm. On the other hand, FIGS.20 and 21 show photographs of the adhering face in trace of a test pieceformed by adhesion of paired AL-alloy A7075 pieces in dimensions of 100mm×25 mm×3 mm with the above “EW2040” according to the presentdisclosure and exhibiting tensile strength of adhesion of 103 MPa (atthe temperature of 18° C.). This broken face is a face of broken resinviewed with a magnifier and such site could not be seen where metalphase is exposed. Most area of the broken face seemed to be of thebroken resin layer adhering to the metal and the tensile strength of thecured “EW2040” was presumed to be almost near the value in breaking ofthe cured adhesive itself as above described.

(5) Measurement of Strength of Adhesion

Methods for measuring shear strength of adhesion and tensile strength ofadhesion of articles joined by adhesion are specified in JISK 6849 (ISO6922) and JISK 6850 (ISO 4587), respectively. However, as explainedabove, the strength of adhesion of an article (test piece) formed byjoining paired metal pieces subjected to NAT treatment or New NATtreatment with a one-part epoxy adhesive cannot be measured in thesestandard methods by JIS (ISO). Then, configuration of an article (testpiece) formed by adhesion of metal pieces or of a metal piece and a CFRPpiece with an adhesive, which the inventor used for measurement, isshown in FIGS. 2 and 3. FIG. 2 shows one for measuring shear strength ofadhesion and FIG. 3 shows one for measuring tensile strength ofadhesion.

BEST MODE FOR CARRYING OUT THE DISCLOSURE

The manner of carrying out the present disclosure will be explained withembodiments below.

(a) Observation with an Electron Microscope

Observation was made using an electron microscope of a SEM (scanningelectron microscope) type: “S-4800” (made by Hitachi-seisakusho Co.Ltd., main company in Tokyo, Japan) and “JSM-6700F” (manufactured byNihon-denshi Co. Ltd., main company in Tokyo, Japan) in 1 to 2 kV.

(b) Observation with a Scanning Probe Microscope

“SPM-9600” (manufactured by Shimadzu-seisakusho Co. Ltd., main companyin Tokyo, Japan) was used.

(c) Measurement of Joining Strength of Composites

Using a tensile testing machine “AG-500N/1 kN” (manufactured byShimadzu-seisakusho Co. Ltd., main company in Tokyo, Japan), shearbreaking strength was measured at a tension speed of 10 mm/min.

Preliminary Preparation for Experiment: Obtaining CFRP Pieces

The inventor received a supply of plenty of CFRP pieces with a dimensionof 45 mm×15 mm×3 mm (thickness) that seems to contain CF by 45 to 50%(wt %: similar as referred to also for solution below) from Toray Co.Ltd. (main company in Tokyo, Japan; referred to as Toray, below) inyears of 2011 to 2011. One half of it is “Torayca T800” (made by Toray)as one in which CF of high strength is used. Its tensile strength is 5.9GPa. The other half is “Torayca T300” (made by Toray) with a tensilestrength of 3.5 GPa, as one made using a previous type of CF having atensile strength of about half of the above CF according to requirementby the inventor. The epoxy resin used as the matrix resin of these CFRPpieces seems to be a resin “No. 2500” or “No. 2580” in the catalogue ofToray, either of which is not of a grade providing heat resistingproperty. That is, as construed, while the composition of the prepreg,approximating one of a one-part epoxy adhesive, is ofdicyandiamide-curable type, it is also one of such a kind that curingtemperature is lowered to a level of 130° C. by adding a curingpromoting agent.

Here, the matrix resin used for CFRP of a grade providing heat resistingproperty is ordinarily a copolymer of an epoxy resin and an aromaticdiamine and the tensile strength of its cured entity is rather high at atemperature below 200° C., if the monomer is suitably selected. Theseare used in CFRP prepregs for aircrafts, among which ones having thehighest heat resisting property do not seem to be disseminated in thecommon. Further, the tensile strength, etc., of the cured thermosettingresins prepared from epoxy resin and aromatic diamine is disclosed inPatent Document 14. Most of the cured resins here have tensile strengthof 55 to 60 MPa, which is lower than the tensile strength at an ordinarytemperature of the cured epoxy adhesive “EW2040” the inventor used, aspresumed to be about 100 MPa: see Experiment example 7).

Further, the tensile strength of the cured one-part epoxy adhesive“EP106NL” used in most multipurpose manners in Japan seems to becomparable with the above and the inventor construe that this is a meantensile strength of the cured epoxy resin of a dicyandiamide-curabletype. In short, as to the strength of the cured epoxy resin at anordinary temperature, the strength of an epoxy resin of adicyandiamide-curable type is higher than the strength of a copolymer ofan epoxy resin and an aromatic diamine, but these become in the reversedrelation at a high temperature.

Here, regarding laminated structure of the acquired CFRP pieces, theCFRP is formed so as to consist of 11 layers of prepreg containing CFbundles collected in a plane direction with CFs arranged in thelongitudinal direction and the thickness of each layer in the curedstate is 0.25 mm for 10 layers and 0.5 mm for the central layer (seeFIG. 15).

Experiment Example 1: NAT Treatment of Al-Alloy

Sheet stocks of Al-alloy A7075 having a thickness of 3 mm were acquiredand machined to form a plurality of small pieces with a dimension of 45mm×15 mm×3 mm. Further, a plurality of small pieces with a dimension of100 mm×25 mm×3 mm were formed by machining from the same Al-alloy sheetstocks. An aqueous solution containing degreaser for aluminum “NE-6”(made by Meltex co. Ltd., main company in Tokyo, Japan) by 10% was madeready to be at 60° C. in a tank, in which the above alloy pieces wereimmersed for 5 minutes, and after then the pieces were rinsed with tapwater (Ota city, Gumma prefecture, Japan). Next, an aqueous solution ofhydrochloric acid having a concentration of 1% was made ready to be at40° C. in another tank, in which the pieces were immersed for 1 minuteand after then the pieces were rinsed with water. Next, an aqueoussolution of caustic soda having a concentration of 1.5% was made readyto be at 40° C. in still another tank, in which the pieces were immersedfor 4 minutes and after then rinsed with water.

Further, an aqueous solution of nitric acid having a concentration of 3%was made ready to be at 40° C., in which the alloy pieces were immersedfor 3 minutes and after then rinsed with water. Next, an aqueoussolution of hydrazine hydrate having a concentration of 3.5% was madeready to be at 60° C., in which the alloy pieces were immersed for 2minutes. Next, an aqueous solution of hydrazine hydrate having aconcentration of 0.5% was made ready to be at 40° C., in which the alloypieces were immersed for 0.5 minutes and after then rinsed with water.Next, the pieces were placed in a warm air drying machine set to be at67° C. for 15 minutes for drying. After drying, the alloy pieces werecollected together, wrapped with aluminum foil and then placed in aplastic bag, which was closed and stored. FIG. 4 shows an electronmicroscopic photograph (magnification of 10,000 times and 100,000 times)of the surface of Al-alloy A7075 subjected to the same treatment as theabove. The schematic view of FIG. 1(b) was presumed seeing thisphotograph along with other material (Patent Document 13).

Experiment Example 2: New NAT Treatment of Al-Alloy

Sheet stocks of Al-alloy A7075 having a thickness of 3 mm were acquiredand machined to form a plurality of small pieces with a dimension of 45mm×15 mm×3 mm. Further, a plurality of small pieces with a dimension of100 mm×25 mm×3 mm were formed by machining from the same Al-alloy sheetstocks. An aqueous solution containing degreaser for aluminum “NE-6” by10% was made ready to be at 60° C. in a tank, in which the above alloypieces were immersed for 5 minutes, and after then the pieces wererinsed with tap water (Ota city, Gumma prefecture, Japan). Next, anaqueous solution of hydrochloric acid having a concentration of 1% wasmade ready to be at 40° C. in another tank, in which the pieces wereimmersed for 1 minute and after then the pieces were rinsed with water.Next, an aqueous solution of caustic soda having a concentration of 1.5%was made ready to be at 40° C., in which the alloy pieces were immersedfor 4 minutes and after then rinsed with water.

Further, an aqueous solution of nitric acid having a concentration of 3%was made ready to be at 40° C., in which the alloy pieces were immersedfor 3 minutes and after then rinsed with water. Next, an aqueoussolution of hydrazine hydrate having a concentration of 3.5% was madeready to be at 60° C., in which the alloy pieces were immersed for 1minute. Next, an aqueous solution of hydrazine hydrate having aconcentration of 0.5% was made ready to be at 33° C., in which the alloypieces were immersed for 3 minutes and after then rinsed with water.Next, an aqueous solution of hydrogen peroxide having a concentration of1.5% was made ready, in which the alloy pieces were immersed for 0.5minute and after then rinsed with water. Next, the pieces were placed ina warm air drying machine set to be at 67° C. for 15 minutes for drying.After drying, the alloy pieces were collected together, wrapped withaluminum foil and then placed in a plastic bag, which was closed andstored. FIG. 5 shows an electron microscopic photograph (magnificationof 100,000 times) of the surface of Al-alloy A7075 subjected to the sametreatment as the above. This treatment method of Al-alloy corresponds toone changed from one in Experiment Example 1 considering the latter hasnot attained sufficiently the sectional schematic view of FIG. 1(b) yet.

Experiment Example 3: NAT Treatment of Stainless Steel (ReferentialExample)

Sheet stocks of stainless steel SUS304 having a thickness of 3 mm wereacquired and machined to form a plurality of small pieces with adimension of 45 mm×15 mm×3 mm. Further, a plurality of small pieces witha dimension of 100 mm×25 mm×3 mm were formed by machining from the samestainless sheet stocks. An aqueous solution containing degreaser foraluminum “NE-6” (made by Meltex co. Ltd., main company in Tokyo, Japan)by 10% was made ready to be at 60° C. in a tank, in which the abovesteel pieces were immersed for 5 minutes, and after then the pieces wererinsed with tap water (Ota city, Gumma prefecture, Japan). Next, anaqueous solution of caustic soda having a concentration of 1.5% was madeready to be at 40° C. in another tank, in which the steel pieces wereimmersed for 1 minute and after then rinsed with tap water. Next, anaqueous solution of sulfuric acid having a concentration of 5% was madeready to be at 65° C., in which the steel pieces were immersed for 4minutes and after then rinsed with water.

Further, an aqueous solution of nitric acid having a concentration of 3%was made ready to be at 40° C., in which the steel pieces were immersedfor 3 minutes and after then rinsed with tap water. Next, the steelpieces were placed in a warm air drying machine set to be at 80° C. for15 minutes for drying. After drying, the alloy pieces were collectedtogether, wrapped with aluminum foil and then placed in a plastic bag,which was closed and stored. FIG. 6 shows an electron microscopicphotograph (magnification of 10,000 times and 100,000 times) of thesurface of the piece of stainless steel SUS304 subjected to the sametreatment as the above. The sectional schematic view of FIG. 1(c) wasdepicted seeing this photograph. That is, the sectional schematic viewof FIG. 1(c) was depicted on the basis of the photograph.

Experiment Example 4: NAT Treatment of Common Steel (ReferentialExample)

Sheet stocks of cold rolled steel plate (SPCC) having a thickness of 3.2mm were acquired and machined to form a plurality of small pieces with adimension of 45 mm×18 mm×3.2 mm. Further, a plurality of small pieceswith a dimension of 100 mm×25 mm×3.2 mm were formed by machining fromthe same steel sheet stocks. An aqueous solution containing degreaser“NE-6” (made by Meltex co. Ltd., main company in Tokyo, Japan) by 10%was made ready to be at 60° C. in a tank, in which the above steelpieces were immersed for 5 minutes, and after then the pieces wererinsed with tap water (Ota city, Gumma prefecture, Japan). Next, anaqueous solution of caustic soda having a concentration of 1.5% was madeready to be at 40° C. in another tank, in which the steel pieces wereimmersed for 1 minute and after then rinsed with tap water.

Further, an aqueous solution of sulfuric acid having a concentration of5% was made ready to be at 60° C., in which the steel pieces wereimmersed for 4 minutes and after then rinsed with water. Next, anaqueous solution of ammonia having a concentration of 1% was made ready,in which the steel pieces were immersed for 1 minute and after thenrinsed with water. Next, an aqueous solution containing 1.2%-chromiumnitrate hydrate, 0.3%-chromium trioxide, 1.5%-phosphoric acid and0.033%-basic nickel carbonate was made ready, in which the steel pieceswere immersed for 1.5 minutes and after then rinsed with water. Next,the steel pieces were placed in a warm air drying machine set to be at80° C. for 15 minutes for drying. After drying, the alloy pieces werecollected together, wrapped with aluminum foil and then placed in aplastic bag, which was closed and stored. FIG. 7 shows an electronmicroscopic photograph (magnification of 10,000 times and 100,000 times)of the surface of the steel piece subjected to the same treatment as theabove. The sectional schematic view of FIG. 1(d) was depicted seeingthis photograph.

Experiment Examination 5: NAT Treatment of Pure Titanium (ReferentialExample)

Sheet stocks of a first species of pure titanium “KS-40” (made byKobe-seikousho Co. Ltd., main company in Hyogo prefecture, Japan) havinga thickness of 3 mm were acquired and machined to form a plurality ofsmall pieces with a dimension of 45 mm×15 mm×3 mm. An aqueous solutioncontaining aluminum degreaser “NE-6” (made by Meltex co. Ltd., maincompany in Tokyo, Japan) by 10% was made ready to be at 60° C. in atank, in which the above titanium pieces were immersed for 5 minutes andafter then the pieces were rinsed with tap water (Ota city, Gummaprefecture, Japan). Next, an aqueous solution of caustic soda having aconcentration of 1.5% was made ready to be at 40° C. in another tank, inwhich the pieces were immersed for 1 minutes and after then the pieceswere rinsed with water.

Further, an aqueous solution of an all-purpose etching agent “KA3” (madeby Kinzokukakougijutsu-kenkyusho Co. Ltd., main company in Tokyo, Japan)having a concentration of 2% was made ready to be at 65° C., in whichthe above titanium pieces were immersed for 3 minutes and after thenrinsed with water. Next, the pieces were placed in a warm air dryingmachine set to be at 80° C. for 15 minutes for drying. After drying, thetitanium pieces were collected together, wrapped with aluminum foil andthen placed in a plastic bag, which was closed and stored. FIG. 8 showsan electron microscopic photograph (magnification of 10,000 times and100,000 times) of the surface of the piece of first species of puretitanium subjected to the same treatment as the above. The schematicview of FIG. 1(e) was depicted seeing this photograph.

Experiment Examination 6: New NAT Treatment of Pure Titanium, TitaniumAlloy (Referential Example)

Sheet stocks of a second species of pure titanium “TP340” (made byShinnitetsu-sumikin Co. Ltd., main company in Tokyo, Japan) having athickness of 3 mm were acquired and machined to form a plurality ofsmall pieces with a dimension of 45 mm×15 mm×3 mm. Further, a pluralityof small pieces with a dimension of 100 mm×25 mm×3 mm were formed bymachining from the same sheet stocks. An aqueous solution containingdegreaser for aluminum “NE-6” (made by Meltex co. Ltd., main company inTokyo, Japan) by 10% was made ready to be at 60° C. in a tank, in whichthe above titanium pieces were immersed for 5 minutes and after then thepieces were rinsed with tap water (Ota city, Gumma prefecture, Japan).Next, an aqueous solution of caustic soda having a concentration of 1.5%was made ready to be at 40° C. in another tank, in which the pieces wereimmersed for 1 minute and after then the pieces were rinsed with water.Next, an aqueous solution of an all-purpose etching agent “KA3” having aconcentration of 2% was made ready to be at 65° C. in still anothertank, in which the above titanium pieces were immersed for 3 minutes andafter then rinsed with water. Next, the titanium pieces were immersed inan aqueous solution having a concentration of 3% and being at 40° C. for3 minutes and after then rinsed with water. Next, the titanium pieceswere immersed in an aqueous solution containing 5%-sodium chlorite and10%-caustic soda and being at 55° C. for 10 minutes and after thenrinsed with water. Next, the pieces were placed in a warm air dryingmachine set to be at 80° C. for 15 minutes for drying. After drying, thetitanium pieces were collected together, wrapped with aluminum foil andthen placed in a plastic bag, which was closed and stored.

FIG. 9 shows electron microscopic photographs of the surface of thepiece of second species of pure titanium subjected to the same treatmentas the above, in which FIG. 9-1 is in magnification of 1,000 times, FIG.9-2 is in magnification of 10,000 times and FIG. 9-3 is in magnificationof 100,000 times, respectively. One in 100,000 times is specificallyremarkable, in which net-shaped configuration covers whole face and theperiod of convex-concave in the net-shape is observed to be 20 to 200nm. While this is a configuration of irregular convex-concave pattern innet-shape in which the period of convex-concave in ultrafineirregularities is dispersed from small to large randomly, itapproximates the sectional schematic view shown in FIG. 1(f) as a whole.

While it is not clear why the above configuration of ultrafinenet-shaped convex-concave is formed, a probe was made as to whethersimilar configuration can be formed or not for titanium alloys havinghigher hardness than a pure titanium. As a result, titanium alloyshaving such configuration of ultrafine net-shaped convex-concave wereobtained by performing oxidization treatment of α-β titanium alloy“KSTI-9” (made by Kobe-seikousho Co. Ltd., main company in Hyogoprefecture, Japan) and α-β titanium alloy “KS6-4” (made byKobe-seikousho Co. Ltd., main company in Hyogo prefecture, Japan). FIG.10-1 to FIG. 10-3 and FIG. 11-1 to FIG. 11-3 are electron microscopicphotographs of such surface configuration. The configuration in FIG.10-2 is analogous to one in FIG. 1(g) and the configuration in FIG. 11-1is analogous to one in FIG. 1(i).

Experiment Examination 7: NAT Treatment of Copper

Sheet stocks of copper CC1100 having a thickness of 3 mm were acquiredand machined to form a plurality of small pieces with a dimension of 45mm×15 mm×3 mm. Further, a plurality of small pieces with a dimension of100 mm×25 mm×3 mm were formed by machining from the same copper sheetstocks. An aqueous solution containing degreaser “NE-6” by 10% was madeready to be at 60° C. in a tank, in which the above copper pieces wereimmersed for 5 minutes and after then the pieces were rinsed with tapwater (Ota city, Gumma prefecture, Japan). Next, an aqueous solution ofcaustic soda having a concentration of 1.5% was made ready to be at 40°C. in another tank, in which the copper pieces were immersed for 1minute and after then rinsed with water. Next, an aqueous solution ofnitric acid having a concentration of 10% was made ready to be at 40° C.in still another tank, in which the copper pieces were immersed for 0.5minute. Next, an aqueous solution of nitric acid having a concentrationof 3% was made ready to be at 40° C., in which the copper pieces wereimmersed for 10 minutes and after then rinsed with water.

Further, an aqueous solution containing potassium permanganate by 2% andcaustic potassium by 3% was made ready to be at 70° C., in which thecopper pieces was immersed for 35 minutes and after then rinsed withwater. Next, the copper pieces were immersed in an aqueous solutioncontaining sodium chlorite by 5% and caustic soda by 10% and being at55° C. for 10 minutes and after then rinsed with water. Next, the copperpieces were placed in a warm air drying machine set to be at 80° C. for15 minutes for drying. After drying, the copper pieces were collectedtogether, wrapped with aluminum foil and then placed in a plastic bag,which was closed and stored.

FIG. 12 shows electron microscopic photographs of the surface of thecopper C1100 piece subjected to the same treatment as the above, inwhich FIG. 12-1 is in magnification of 10,000 times and FIG. 12-2 is in100,000 times. As seen in FIG. 12-2 (photograph in 100,000 times), thewhole face is covered with surface configuration of ultrafineirregularities in which rectangular parallelepiped pieces with a sidedimension of 10 to 200 nm stand on a plain in number density of 10 to 20in a square of 200 nm×200 nm. In short, this approximates the visage inFIG. 1(j).

Experiment Examination 8: New NAT Treatment of Copper (ReferentialExample)

Sheet stocks of copper CC1100 having a thickness of 3 mm were acquiredand machined to form a plurality of small pieces with a dimension of 45mm×15 mm×3 mm. Further, a plurality of small pieces with a dimension of100 mm×25 mm×3 mm were formed by machining from the same copper sheetstocks. An aqueous solution containing degreaser “NE-6” by 10% was madeready to be at 60° C. in a tank, in which the above copper pieces wereimmersed for 5 minutes and after then the pieces were rinsed with tapwater (Ota city, Gumma prefecture, Japan). Next, an aqueous solution ofcaustic soda having a concentration of 1.5% was made ready to be at 40°C. in another tank, in which the copper pieces were immersed for 1minute and after then rinsed with water. Next, an aqueous solution ofnitric acid having a concentration of 10% was made ready to be at 40° C.in still another tank, in which the copper pieces were immersed for 0.5minute. Next, an aqueous solution of nitric acid having a concentrationof 3% was made ready to be at 40° C., in which the copper pieces wereimmersed for 10 minutes and after then rinsed with water.

Further, an aqueous solution containing 10%-sulfuric acid and4%-hydrogen peroxide was made ready to be at 25° C. in still anothertank, in which the copper pieces were immersed for 3 minutes and afterthen rinsed with water. Next, an aqueous solution containing potassiumpermanganate by 2% and caustic potassium by 3% was made ready to be at70° C., in which the copper pieces was immersed for 35 minutes and afterthen rinsed with water. Next, the copper pieces were immersed in anaqueous solution containing sodium chlorite by 5% and caustic soda by10% and being at 55° C. for 10 minutes and after then rinsed with water.Next, the copper pieces were placed in a warm air drying machine set tobe at 80° C. for 15 minutes for drying. After drying, the copper pieceswere collected together, wrapped with aluminum foil and then placed in aplastic bag, which was closed and stored.

FIG. 13 shows electron microscopic photographs of the surface of thecopper C1100 piece subjected to the same treatment as the above, inwhich FIG. 13-1 is in magnification of 1,000 times, FIG. 13-2 is in10,000 times and FIG. 13-3 is in 100,000 times. As seen in FIG. 13-3(photograph in 100,000 times), the surface configuration is such thatwhiskers grow like hairs on head densely, the whiskers are long and thebase ground is not seen, while the whiskers seem to cross and beentangled among them. It is a question whether adhesive can sufficientlypenetrate into the root of the whiskers. The inventor considers ofmaking the whiskers have a length below one half to be of erectshortened hair type. The configuration in FIG. 1(k) is a schematic viewshowing the shortened hair type when it is accomplished.

Experiment Example 9: NAT Treatment of Mg-Alloy

Sheet stocks of magnesium alloy AZ31B having a thickness of 1 mm wereacquired and machined to form a plurality of small pieces with adimension of 45 mm×15 mm×1 mm. An aqueous solution containing degreaserfor magnesium alloy “Cleaner160” (Meltex Co. Ltd. main company in Tokyo,Japan) by 10% was made ready to be at 60° C. in a tank, in which theabove magnesium alloy pieces were immersed for 5 minutes and after thenthe alloy pieces were rinsed with tap water (Ota city, Gumma prefecture,Japan). Next, an aqueous solution of citric acid hydrate having aconcentration of 1% was made ready to be at 40° C. in another tank, inwhich the alloy pieces were immersed for 4 minutes and after then rinsedwith water. Next, an aqueous solution containing sodium carbonate by 1%and sodium bicarbonate by 1% was made ready to be at 65° C. in stillanother tank, in which the alloy pieces were immersed for 5 minutes.Next, an aqueous solution of caustic soda having a concentration of 15%was made ready to be at 65° C. in still another tank, in which the alloypieces were immersed for 5 minutes and after then rinsed with water.

Further, an aqueous solution of citric acid hydrate having aconcentration of 0.25% was made ready to be at 40° C. in another tank,in which the alloy pieces were immersed for 1 minute and after thenrinsed with water. Next, the rinsed alloy pieces were immersed in anaqueous solution containing 2%-potassium permanganate, 1%-acetic acidand 0.5%-sodium acetic acid hydrate and being at 45° C. for 1 minute andafter then rinsed with water. Next, the alloy pieces were placed in awarm air drying machine set to be at 80° C. for 15 minutes for drying.After drying, the alloy pieces were collected together, wrapped withaluminum foil and then placed in a plastic bag, which was closed andstored. FIG. 14 shows electron microscopic photographs of the surface ofthe magnesium alloy AZ31B piece subjected to the same treatment as theabove in magnification of 100,000 times. FIG. 1(l) was depicted seeingFIG. 14.

Experiment Examination 10: Preparation of Pieces Formed by NAT Adhesionand Measurement of Shear Strength

Using paired pieces for forming test pieces of the metal or metal alloysobtained with Examination Examples 1 to 9: of Al-alloy A7075, stainlesssteel SUS304, cold rolled steel plate SPCC, first species of puretitanium “KS-40”, α-β Ti-alloy “KSTI-9”, α-β Ti-alloy “KS6-4”, copperC1100 and magnesium alloy AZ31B, test pieces shown in FIG. 2 wereprepared by adhesion of the paired pieces according to NAT with aone-part epoxy adhesive.

That is, about 2 g of MIBK (methylisobuthylketone) was added to 3 g ofthe above described adhesive and stirred sufficiently, thus obtaining asuspension. Then, one end portion with about 4 mm width of each metalsmall piece with a dimension of 45 mm×15 mm×(3 to 3.5) mm having beensubjected to surface treatment was painted sufficiently with the aboveobtained suspension using the tip of a stick. The metal small pieceswere placed in a hot air drying machine set to be at 55° C. for 20minutes, causing MIBK to be volatilized. The metal small pieces werethen taken out and painted additionally with the previous adhesive (sameas the above). After then, the ends of the metal small pieces paintedwith adhesive were joined to form a paired piece (test piece). Each ofthus formed paired pieces was fixed with two clips. The paired pieces inthe fixed state were placed in a hot air drying machine set to be at135° C., then after temperature was raised to 170° C. the pieces werekept there for 15 minutes to heat them and after then taken out of thedrying machine.

The test pieces were kept in a state where the clips were taken off. Onthe next day, the test pieces were subjected to tensile breaking test tomeasure shear breaking strength of adhesion of these test pieces. Here,as Mg-alloy pieces had thickness of 1 mm, 3 pieces of these painted withadhesive were layered to form a piece, thus 6 Mg-alloy small piecesresulted in forming one test piece for measurement. Then, 5 test pieces,each of which was joined by adhesion, were prepared for each species ofmetal or metal alloy and broken in test to record mean shear strength ofadhesion. The result of test is shown in the following Table 1. As canbe said from Table 1, while the shear strength of adhesion of a firstspecies of pure titanium is somewhat low, the tensile strength ofadhesion of other metals or metal alloys is sufficiently high. When thebroken face was actually observed, such site could not be seen wheremetal portion is exposed on the broken faces of both sides. Thus. it wasfound that excellent adhesion was made.

TABLE 1 Shear Strength of Adhesion of Various Metals or Metal AlloysJoined with One-part Epoxy Adhesive Shear Metal Photo- ClassificationStrength Metal Species Treatment graph by FIG. 1 of Adhesion Al-alloyA7075 NAT FIG. 4  (b) 79 MPa Al-alloy A7075 New NAT FIG. 5  (b) 81 MPaStainless Steel SUS304 NAT FIG. 6  (c) 73 MPa Cold rolled Steel PlateNAT FIG. 7  (d) 73 MPa (SPCC) 1st Species of Pure NAT FIG. 8  (e) 65 MPaTitanium 2nd Species of Pure New NAT FIG. 9  (f) 78 MPa Titanium α-βTi-alloy KSTI-9 New NAT FIG. 10 (h) 80 MPa α-β Ti-alloy KS6-4 New NATFIG. 11 (i) 80 MPa Copper C1100 New NAT FIG. 12 (j) 79 MPa Copper C1100New NAT FIG. 13 (k) 80 MPa Magnesium Alloy AZ31B NAT FIG. 14 (1) 81 MPa

Experiment Example 11: Preparation of Pieces Formed by NAT Adhesion andMeasurement of Tensile Strength of Adhesion

Using paired pieces for forming test pieces of the metal or metal alloysobtained with Examination Examples 1 to 5: of Al-alloy A7075, stainlesssteel SUS304, cold rolled steel plate SPCC, first species of puretitanium “KS-40”, second species of pure titanium “TP340”, α-β Ti-alloy“KSTI-9” and α-β Ti-alloy “KS6-4”, test pieces shown in FIG. 3 wereprepared by adhesion of the paired pieces according to NAT with aone-part epoxy adhesive “Scotch Weld EW2040” (made by Three M Japan Co.Ltd.: Main company in Tokyo, Japan).

That is, about 2 g of MIBK was added to 3 g of the above describedadhesive and stirred sufficiently, thus obtaining a suspension. Then,one edge face (face of 25 mm×3 mm) of each metal small piece with adimension of 100 mm×25 mm×3 mm having been subjected to surfacetreatment was painted sufficiently with the above obtained suspensionusing the tip of a stick. The metal small pieces were placed in a hotair drying machine set to be at 55° C. for 20 minutes, causing MIBK tobe volatilized. The metal small pieces were then taken out and paintedadditionally with the adhesive. After then, the end faces of pairedmetal small pieces painted with adhesive were caused to abut on eachother and form a pair. Winding TEFRON seal tape around the joinedportion of the pair, fixing the portion with two clips and pushing thepair at the both ends, the thickness of the adhesive was approximated tozero. After then, the adhesive were cured in the hot air drying machinein a similar manner as in Experiment Examination 6.

The test pieces were taken out of the drying machine and clips weretaken off. On the next day, peeling off the TEFRON seal tape, the curedadhesive protruding out of the joined face was ground away so that thearea of adhesion is of (below 25 mm)×(below 3 mm), that is, 0.7 to 0.73cm². The test pieces were broken in tensile strength test to measuretensile strength of adhesion. The following Table 2 shows the result ofthe test in which the highest tensile strength of the data obtained with5 pairs of test pieces for each metal species by breaking these in testis recorded.

TABLE 2 Tensile Strength of Adhesion of Various Metals or Metal Alloysjoined with One-Part Epoxy Adhesive Tensile Metal ClassificationStrength Metal Species Treatment Photograph by FIG. 1 of AdhesionAl-alloy A7075 NAT FIG. 4 (b) 81 MPa Al-alloy A7075 New NAT FIG. 5 (b)103 MPa  Stainless Steel SUS304 NAT FIG. 6 (c) 59 MPa Cold rolled SteelPlate NAT FIG. 7 (d) 67 MPa (SPCC) 1st Species of Pure NAT FIG. 8 (e) 60MPa Titanium 2nd Species of Pure New NAT FIG. 9 (f) 85 MPa Titanium α-βTi-alloy KSTI-9 New NAT  FIG. 10 (h) 97 MPa α-β Ti-alloy KS6-4 New NAT FIG. 11 (i) 98 MPa Copper C1100 New NAT  FIG. 12 (j) 80 MPa CopperC1100 New NAT  FIG. 13 (k) 62 MPa

As can be said from Table 2, the tensile strength of test pieces shownin FIGS. 5, 10 and 11 was about 100 MPa and the highest value was 103.2MPa that Al-alloy shown in FIG. 5 exhibited. The test piece thatexhibited high tensile strength of adhesion next to this was one shownin FIG. 9, and further test pieces shown in FIGS. 4 and 12 exhibitedapproximately 80 MPa. In these, the tensile strength was same as orhigher than the shear strength.

Here, FIGS. 20 and 21 show photographs of the test pieces formed byjoining paired small pieces of Al-alloy A7075 that exhibited tensilestrength of adhesion of 103.2 MPa as above. While FIG. 20 shows thesituation in which fragmentary pieces of the test piece broken in testare arranged side by side as before breaking, FIG. 21 shows a close-upphotograph of a trace of the adhesion face. While the thickness ofadhesive layer was taken as 0.17 mm as determined from the measurementdata of the length of the test piece before breaking in test, the testpiece was split into two fragments near the center of the adhesive layerand metal face could not be seen in the trace of adhesion face byobservation with a magnifier. Consequently, it was presumed that thestrength of adhesion is of a value same as or near to the tensilestrength of the cured adhesive “EW2040”.

The tensile strength of Al-alloy A7075 clearly increased by changingfrom NAT treatment to New NAT treatment. While new strange linear shapesappear in electron microscopic photographs with transition from FIG. 4to FIG. 5, the inventor did not consider that the linear shapes broughtan effect, but presumed they were brought because the configuration ofultrafine bowl-shaped concaves was neatened by shortening the time ofimmersion in hydrazine hydrate to a half. Although SPCC has highstrength among those below 80 MPa, it is clearly different from theabove four species. Stainless steel SUS304 and the first species of puretitanium by NAT treatment have low strength. The high-low of strength isas supposed in FIG. 1 and can be understood seeing electron microscopicphotographs.

Experiment Examination 12: Composite of a Metal Piece and a CFRP PieceFormed by NAT Adhesion and Shear Strength of Adhesion

Using metal pieces obtained with Examination Examples 2 to 6: ofAl-alloy A7075, stainless steel SUS304, cold rolled steel plate SPCC,α-β Ti-alloy “KSTI-9”, α-β Ti-alloy “KS6-4”, and two kinds of CFRPpieces for each metal piece, test pieces shown in FIG. 2 were preparedby adhesion of the paired metal piece and CFRP piece according to NATwith a one-part epoxy adhesive “Scotch Weld EW2040”.

That is, about 2 g of MIBK was added to 1 g of the above describedadhesive and stirred sufficiently, thus obtaining a suspension. Then,one end portion with about 4 mm width of each metal small piece with adimension of 45 mm×15 mm×3 mm having been subjected to surface treatmentwas painted sufficiently with the above obtained suspension using thetip of a stick. On the other hand, regarding also CFRP pieces (FIG. 13)with a dimension of 45 mm×15 mm×3 mm similar to the above that is formedin such a type of fiber bundles arranged in two longitudinal directions,one end portion with about 4 mm of each small piece was groundsufficiently with a sandpaper of #600 to a state where a part of CF isexposed. Then, the small pieces were immersed in a degreaser bath with asupersonic wave devise for several minutes and rinsed with water, afterwhich they were dried at 80° C. with hot air for 15 minutes.

Then, the end portion of each CFRP piece were painted sufficiently witha solvent containing adhesive with the tip of a stick in a similarmanner as metal small pieces. The CFRP pieces were placed in a warm airdrying machine set to be at 55° C. for 20 minutes with MIBK volatilized,then taken out and painted additionally with the adhesive. After then,the end portion of each of the CFRP pieces and the end portion of metalsmall pieces painted with adhesive were joined to form a paired piece(test piece). Each of thus formed paired pieces was fixed with twoclips. The paired pieces in the fixed state were placed in a hot airdrying machine set to be at 135° C., then the temperature was raised to170° C. and the paired pieces were kept there for 15 minutes and takenout after then. The shear strength of adhesion of the test piecesobtained through the operation were measured and the average shearstrength of adhesion of 5 paired pieces is shown in Table 3. It wasclear that the strength in result is almost decided depending on the CFcontained in CFRP. As regards the face of breaking, breaking did notoccur at the interface between the metal part and the CFRP part, but thesurface layer of the CFRP was broken. A certain amount of carbon fiberhad adhered to the trace of broken face on the side of the metal part.In short, the strength of adhesion was exhibited as a result such thatthe strength of adhesion between CF within the CFRP and the matrix resinappeared itself.

TABLE 3 Strength of Adhesion of CFRP with Various Metals or MetalAlloys: Shear Strength of Adhesion Shear Metal Classification StrengthMetal Species Treatment Photograph by FIG. 1 of Adhesion CFRTP (CF of 6Gpa is used) Al-Alloy A7075 New NAT FIG. 5 (b) 41 MPa Stainless SteelSUS304 NAT FIG. 6 (c) 40 MPa Cold Rolled Steel Plate NAT FIG. 7 (d) 41MPa (SPCC) α-β Ti-alloy KSTI-9 New NAT  FIG. 10 (h) 43 MPa α-β Ti-alloyKS6-4 New NAT  FIG. 11 (i) 40 Mpa CFRTP (CF of 3.5 Gpa is used) Al-AlloyA7075 New NAT FIG. 5 (b) 59 MPa Stainless Steel SUS304 NAT FIG. 6 (c) 58MPa Cold Rolled Steel Sheet NAT FIG. 7 (d) 57 MPa (SPCC) α-β Ti-alloyKSTI-9 New NAT  FIG. 10 (h) 59 MPa α-β Ti-alloy KS6-4 New NAT  FIG. 11(i) 59 MPa

Experiment Example 13: Composite of a Metal Piece and a CFRP PieceFormed by NAT Adhesion and Shear Strength of Adhesion

Regarding two kinds of CFRP pieces (FIG. 15) acquired from Toray co.Ltd. and sized to be 45 mm×15 mm×3 mm, it was tried to measure two kindsof tensile strength of adhesion of the test pieces each of which wasformed by adhesion of the CFRP piece and a metal small piece. The reasonfor this is that the CFRP pieces were of a longitudinal fiber bundletype. Specifically, the shape of the metal piece was changed in order toprevent the CFRP piece from being damaged by impact to create flaw, thustest pieces of paired pieces as shown in FIGS. 16 and 17 were prepared.That is, pieces of Al-alloy A7075, stainless steel SUS304 and α-βTi-alloy “KS6-4” with a dimension of 45 mm×15 mm×3 mm were prepared andthese metal pieces were subjected to NAT treatment or New NAT treatment.The end face or side face of each of these metal pieces was used for aface of adhesion. Also regarding each CFRP piece, the face for adhesionwas treated with a sandpaper of #600, cleaned under supersonic waves andsubjected to roughening treatment in a similar manner as the aboveExperiment Examination. After then, each metal piece and CFRP piece werebonded by adhesion using a one-part epoxy adhesive “EW2040” according toNAT including treatment of “impregnation”.

After articles formed by adhesion shown in FIGS. 16 and 17 wereobtained, these were broken in test with a tensile tester and thetensile strength of adhesion was measured. The result was shown inTables 4 and 5. Having observed the face of breaking in all the testpieces shown in Tables 4 and 5, adhering resin portion was seen in allthe area of the trace of adhesion on the side of the metal part andscrapped CF was not seen there at all. Further, any tip of peeled CFportion was not be seen there. In short, it was clarified to be materialbreaking in both materials (cured matrix resin and cured adhesive).

TABLE 4 Strength of Adhesion of CFRP with Metals or Metal Alloys:Tensile Strength of Adhesion in the Same Direction as CF Tensile MetalClassification Strength Metal Species Treatment Photograph by FIG. 1 ofAdhesion CFRTP (CF of 6 Gpa is used) Al-Alloy A7075 New NAT FIG. 5 (b)58 MPa Stainless Steel SUS304 NAT FIG. 6 (c) 56 MPa α-β Ti-alloy KS6-4New NAT  FIG. 11 (i) 58 MPa

TABLE 5 Strength of Adhesion of CFRP with Metals or Metal Alloys:Tensile Strength of Adhesion in the Direction perpendicular to CFTensile Metal Classification Strength Metal Species Treatment Photographby FIG. 1 of Adhesion CFRTP (CF of 6 Gpa is used) Al-Alloy A7075 New NATFIG. 5 (b) 57 MPa Stainless Steel SUS304 NAT FIG. 6 (c) 57 MPa α-βTi-alloy KS6-4 New NAT  FIG. 11 (i) 58 MPa

CFRP pieces having been made using a new type of CF with high strengthwas used. It is known that the strength of adhesion between CF andmatrix resin within the CFRP is at most about 40 MPa. Although CFRP issuch, the tensile strength of the composite formed by bonding the CFRPpiece and a metal piece by adhesion exhibited approximately 60 MPa.Further, such a result was obtained that the strength is not related tothe direction of fiber arrangement. Compared with these data of tensilestrength of adhesion, the data of shear strength of adhesion shown inFIG. 3 shows a result quite different from ones of tensile strength ofadhesion.

It is obvious that the difference is caused by the laminated structureof prepreg. While prepreg sheets are formed usually containing CFbundled longitudinally, the direction of fiber arrangement is parallelwith sheet surface and matrix resin fills the gap space connecting upperand lower surfaces of fiber bundle. If the strength of adhesion betweenthe CF and the matrix resin is about 40 MPa, it is natural that theshear breaking occurs at the face of parallel fiber bundles at themoment of shear breaking. In short, in the case where surface treatmentof metal part is brought to an ideal level as shown by the presentdisclosure, it can be understood that what can be done first with a CFRPas the adherend part is to vary the direction of prepreg arrangement.

What is claimed is:
 1. A method for producing a metal containingcomposite, comprising: a step of preparing an adhesive (B) containingsolvent and formed as a suspension of low viscosity by adding a ketonesolvent to a one-part epoxy adhesive (A) using dicyandiamide as a curingagent and mixing the same; a step of preparing one kind of metal shapedarticle as an adherend selected from the following five kinds of metalshaped articles (M1 to M5): a metal shaped article (M1), which, throughsurface treatment including chemical etching and/or surface hardening,has a surface with ultrafine irregularities covered entirely withsubstantially ultrafine bowl-shaped concaves of 20 to 100 nm diameterand in which said surface with said ultrafine irregularities is coveredwith a thin layer of ceramics comprising a metal oxide or a metalphosphate, a metal shaped article (M2), which, through surface treatmentincluding chemical etching and/or surface hardening, has a roughenedsurface, in which a forest of convexes shaped like thick walls orconvexes of indefinite shapes as formed by collapse of such thick wallswith short dimension and long dimension of 0.05 to 1 μm and height ofmore than 0.3 μm stand with space of 0.1 to 2 μm therebetween, theroughened surface being entirely covered with ultrafine irregularitieshaving period of 20 to 100 nm and the whole surface being covered with athin layer of ceramics comprising a metal oxide or a metal phosphate, ametal shaped article (M3), which, through surface treatment includingchemical etching and/or surface hardening, has a roughened surfacehaving bowl-like concave faces of 1 to 5 μm period, the roughenedsurface being entirely covered with ultrafine irregularities havingperiod of 20 to 100 nm and the whole surface being covered with a thinlayer of ceramics comprising a metal oxide or a metal phosphate, a metalshaped article (M4), which, through surface treatment including chemicaletching and/or surface hardening, has a surface with ultrafineirregularities covered entirely with cubic protrusions in a dimension of10 to 200 nm or mixed protrusions of such cubic protrusions anddisc-shaped protrusions of 100 to 250 nm diameter standing on a plain ina density of 5 to 50 per square of 200 nm side, the whole surface beingcovered with a thin layer of ceramics comprising a metal oxide or ametal phosphate, and a metal shaped article (M5), which, through surfacetreatment including chemical etching and/or surface hardening, has asurface configuration loaded with spherical entities of about 100 nmdiameter combined among themselves along with a configuration ofnumerous short whiskers below 10 nm growing on the surface of thespherical entities, the whole surface being covered with a thin layer ofceramics comprising a metal oxide or a metal phosphate; a step ofpainting a face for adhesion of said selected metal shaped article (M1to M5) with said adhesive (B) containing solvent and volatilizing theketone solvent in a drying machine or through air-drying; a step ofpreparing a prepreg as a resin shaped article (P2) made of thermosettingepoxy resin composition containing reinforcing fibers as anotheradherend; a step of preparing a jig for shaping adapted for containingsaid prepreg (P2) and said selected one kind of metal shaped article (M1to M5); and a step of loading said prepreg (P2) and said one kind ofmetal shaped article (M1 to M5) in said jig, fastening said jig, placingsaid jig with said prepreg (P2) and metal shaped article (M1 to M5) in aheating container and curing the entire epoxy resin part with determinedoperation to accomplish adhesion of the resin shaped article (P2)containing reinforcing fibers that has been cured as a result and themetal shaped article (M1 to M5), wherein the tensile strength ofadhesion between the metal shaped article and the resin shaped articleis equal to or higher than the shear strength of adhesion.
 2. The methodfor producing the metal containing composite according to claim 1,wherein said ketone solvent is methyl-isobutyl-ketone.
 3. A metalcontaining composite produced by a method for producing the metalcontaining composite, comprising: a step of preparing an adhesive (B)containing solvent and formed as a suspension of low viscosity by addinga ketone solvent to a one-part epoxy adhesive (A) using dicyandiamide asa curing agent and mixing the same; a step of preparing one kind ofmetal shaped article as an adherend selected from the following fivekinds of metal shaped articles (M1 to M5): a metal shaped article (M1),which, through surface treatment including chemical etching and/orsurface hardening, has a surface with ultrafine irregularities coveredentirely with substantially ultrafine bowl-shaped concaves of 20 to 100nm diameter and in which said surface with said ultrafine irregularitiesis covered with a thin layer of ceramics comprising a metal oxide or ametal phosphate, a metal shaped article (M2), which, through surfacetreatment including chemical etching and/or surface hardening, has aroughened surface, in which a forest of convexes shaped like thick wallsor convexes of indefinite shapes as formed by collapse of such thickwalls with short dimension and long dimension of 0.05 to 1 μm and heightof more than 0.3 μm stand with space of 0.1 to 2 μm therebetween, theroughened surface being entirely covered with ultrafine irregularitieshaving period of 20 to 100 nm and the whole surface being covered with athin layer of ceramics comprising a metal oxide or a metal phosphate, ametal shaped article (M3), which, through surface treatment includingchemical etching and/or surface hardening, has a roughened surfacehaving bowl-like concave faces of 1 to 5 μm period, the roughenedsurface being entirely covered with ultrafine irregularities havingperiod of 20 to 100 nm and the whole surface being covered with a thinlayer of ceramics comprising a metal oxide or a metal phosphate, a metalshaped article (M4), which, through surface treatment including chemicaletching and/or surface hardening, has a surface with ultrafineirregularities covered entirely with cubic protrusions in a dimension of10 to 200 nm or mixed protrusions of such cubic protrusions anddisc-shaped protrusions of 100 to 250 nm diameter standing on a plain ina density of 5 to 50 per square of 200 nm side, the whole surface beingcovered with a thin layer of ceramics comprising a metal oxide or ametal phosphate, and a metal shaped article (M5), which, through surfacetreatment including chemical etching and/or surface hardening, has asurface configuration loaded with spherical entities of about 100 nmdiameter combined among themselves along with a configuration ofnumerous short whiskers below 10 nm growing on the surface of thespherical entities, the whole surface being covered with a thin layer ofceramics comprising a metal oxide or a metal phosphate; a step ofpainting a face for adhesion of said selected metal shaped article (M1to M5) with said adhesive (B) containing solvent and volatilizing theketone solvent in a drying machine or through air-drying; a step ofpreparing a resin shaped article (P1) as another adherend by curing athermosetting epoxy resin composition comprising an epoxy resin as amain constituent; a step of forming a roughened face for adhesion of theresin shaped article (P1) with several decades μm order on a specifiedportion of said resin shaped article (P1) by grinding it with physicalmeans, cleaning with water, drying and removing dirt; a step of paintingthe roughened face for adhesion of said resin shaped article (P1) withsaid adhesive (B) containing solvent and volatilizing the ketone solventin a drying machine or through air-drying; and a step of causing theface for adhesion of said selected metal shaped article (M1 to M5) andthe roughened face of adhesion of said resin shaped article (P1), bothof which were painted with the one-part epoxy adhesive to abut on eachother and fixing the metal shaped article and the resin shaped article,heating the fixed shaped articles at a temperature of 150 to 180° C. andcuring the one-part adhesive to accomplish adhesion, wherein said firstmetal shaped article (M1) is of aluminum, of aluminum alloy oraluminum-plated steel sheet, said second metal shaped article (M2) andsaid third metal shaped article (M3) are of first to fourth species ofpure titanium or titanium alloy, said fourth metal shaped article (M4)is of copper or of copper alloy, and said fifth metal shaped article(M5) is of magnesium alloy, and wherein the tensile strength of adhesionbetween the metal shaped article and the resin shaped article is equalto or higher than the shear strength of adhesion.
 4. A metal containingcomposite produced by a method for producing the metal containingcomposite, comprising: a step of preparing an adhesive (B) containingsolvent and formed as a suspension of low viscosity by adding a ketonesolvent to a one-part epoxy adhesive (A) using dicyandiamide as a curingagent and mixing the same; a step of preparing one kind of metal shapedarticle as an adherend selected from the following five kinds of metalshaped articles (M1 to M5): a metal shaped article (M1), which, throughsurface treatment including chemical etching and/or surface hardening,has a surface with ultrafine irregularities covered entirely withsubstantially ultrafine bowl-shaped concaves of 20 to 100 nm diameterand in which said surface with said ultrafine irregularities is coveredwith a thin layer of ceramics comprising a metal oxide or a metalphosphate, a metal shaped article (M2), which, through surface treatmentincluding chemical etching and/or surface hardening, has a roughenedsurface, in which a forest of convexes shaped like thick walls orconvexes of indefinite shapes as formed by collapse of such thick wallswith short dimension and long dimension of 0.05 to 1 μm and height ofmore than 0.3 μm stand with space of 0.1 to 2 μm therebetween, theroughened surface being entirely covered with ultrafine irregularitieshaving period of 20 to 100 nm and the whole surface being covered with athin layer of ceramics comprising a metal oxide or a metal phosphate, ametal shaped article (M3), which, through surface treatment includingchemical etching and/or surface hardening, has a roughened surfacehaving bowl-like concave faces of 1 to 5 μm period, the roughenedsurface being entirely covered with ultrafine irregularities havingperiod of 20 to 100 nm and the whole surface being covered with a thinlayer of ceramics comprising a metal oxide or a metal phosphate, a metalshaped article (M4), which, through surface treatment including chemicaletching and/or surface hardening, has a surface with ultrafineirregularities covered entirely with cubic protrusions in a dimension of10 to 200 nm or mixed protrusions of such cubic protrusions anddisc-shaped protrusions of 100 to 250 nm diameter standing on a plain ina density of 5 to 50 per square of 200 nm side, the whole surface beingcovered with a thin layer of ceramics comprising a metal oxide or ametal phosphate, and a metal shaped article (M5), which, through surfacetreatment including chemical etching and/or surface hardening, has asurface configuration loaded with spherical entities of about 100 nmdiameter combined among themselves along with a configuration ofnumerous short whiskers below 10 nm growing on the surface of thespherical entities, the whole surface being covered with a thin layer ofceramics comprising a metal oxide or a metal phosphate; a step ofpainting a face for adhesion of said selected metal shaped article (M1to M5) with said adhesive (B) containing solvent and volatilizing theketone solvent in a drying machine or through air-drying; a step ofpreparing a prepreg as a resin shaped article (P2) made of thermosettingepoxy resin composition containing reinforcing fibers as anotheradherend; a step of preparing a jig for shaping adapted for containingsaid prepreg (P2) and said selected one kind of metal shaped article (M1to M5); and a step of loading said prepreg (P2) and said one kind ofmetal shaped article (M1 to M5) in said jig, fastening said jig, placingsaid jig with said prepreg (P2) and metal shaped article (M1 to M5) in aheating container and curing the entire epoxy resin part with determinedoperation to accomplish adhesion of the resin shaped article (P2)containing reinforcing fibers that has been cured as a result and themetal shaped article (M1 to M5), wherein said first metal shaped article(M1) is of aluminum, of aluminum alloy or aluminum-plated steel sheet,said second metal shaped article (M2) and said third metal shapedarticle (M3) are of first to fourth species of pure titanium or titaniumalloy, said fourth metal shaped article (M4) is of copper or of copperalloy, and said fifth metal shaped article (M5) is of magnesium alloy,and wherein the tensile strength of adhesion between the metal shapedarticle and the resin shaped article is equal to or higher than theshear strength of adhesion.
 5. The metal containing composite accordingto claim 3, wherein said ketone solvent is methyl-isobutyl-ketone. 6.The metal containing composite according to claim 4, wherein said ketonesolvent is methyl-isobutyl-ketone.